Solid state microwave synthesis of highly crystalline ordered mesoporous hausmannite Mn 3 O 4 films

DOE PAGES

Xia, Yanfeng; Qiang, Zhe; Lee, Byeongdu; ...

2017-06-23

Microwave calcination of ordered micelle templated manganese carbonate films leads to highly crystalline, ordered mesoporous manganese oxide, while similar temperatures in a furnace lead to disordered, amorphous manganese oxide.

Mesoporous carbon incorporated metal oxide nanomaterials as supercapacitor electrodes.

PubMed

Jiang, Hao; Ma, Jan; Li, Chunzhong

2012-08-08

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

Free-standing, well-aligned ordered mesoporous carbon nanofibers on current collectors for high-power micro-supercapacitors.

PubMed

Kang, Eunae; Jeon, Gumhye; Kim, Jin Kon

2013-07-21

The mesoporous carbon nanofiber arrays that stand on carbon-gold double-layer current collectors are synthesized by self-assembly of a PS-b-PEO copolymer and resol in AAO templates for a high-power micro-supercapacitor at high current densities.

A rational repeating template method for synthesis of 2D hexagonally ordered mesoporous precious metals.

PubMed

Takai, Azusa; Doi, Yoji; Yamauchi, Yusuke; Kuroda, Kazuyuki

2011-03-01

A repeating template method is presented for the synthesis of mesoporous metals with 2D hexagonal mesostructures. First, a silica replica (i.e., silica nanorods arranged periodically) is prepared by using 2D hexagonally ordered mesoporous carbon as the template. After that, the obtained silica replica is used as the second template for the preparation of mesoporous ruthenium. After the ruthenium species are introduced into the silica replica, the ruthenium species are then reduced by a vapor-infiltration method by using the reducing agent dimethylamine borane. After the ruthenium deposition, the silica is chemically removed. Analysis by transmission and scanning electron microscopies, a nitrogen-adsorption-desorption isotherm, and small-angle X-ray scattering revealed that the mesoporous ruthenium had a 2D hexagonal mesostructure, although the mesostructural ordering is decreased compared to that of the original mesoporous carbon template. This method is widely applicable to other metal systems. By changing the metal species introduced into the silica replica, several mesoporous metals (palladium and platinum) can be synthesized. Ordered mesoporous ruthenium and palladium, which are not easily attainable by the soft-templating methods, can be prepared. This study has overcome the composition variation limitations of the soft-templating method. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

NASA Astrophysics Data System (ADS)

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

2004-05-01

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

Adsorption of lignite-derived humic acids on coal-based mesoporous activated carbons.

PubMed

Lorenc-Grabowska, Ewa; Gryglewicz, Grazyna

2005-04-15

The adsorption by a coal-based mesoporous activated carbon of humic acids (HAs) isolated from two Polish lignites was studied. For comparison, a commercial Aldrich humic acid was also included into this study. The differences in chemical structure and functional groups of HAs were determined by elemental analysis and infrared spectroscopy DRIFT. Two activated carbons used differed in terms of mesopore volume, mesopore size distribution, and chemical properties of the surface. The kinetics of adsorption of HAs have been discussed using three kinetic models, i.e., the first-order Lagergren model, the pseudo-second-order model, and the intraparticle diffusion model. It was found that the adsorption of HAs from alkaline solution on mesoporous activated carbon proceeds according to the pseudo-second-order model. The correlation coefficients were close to 1. The intraparticle diffusion of HA molecules within the carbon particle was identified to be the rate-limiting step. Comparing the two activated carbons, the carbon with a higher volume of pores with widths of 10-50 nm showed a greater removal efficiency of HA. An increase in the Freundlich adsorption capacity with decreasing carbon content of HA was observed. Among the HAs studied, S-HA shows characteristics indicating the highest contribution of small-size fraction. The S-HA was removed by both activated carbons to the highest extent. The effect of pH solution on the adsorption of HA was examined over the range pH 5.4-12.2. It was found that the extent of adsorption decreased with decreasing pH of the solution.

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

PubMed

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

2017-10-04

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

Synthesis of non-siliceous mesoporous oxides.

PubMed

Gu, Dong; Schüth, Ferdi

2014-01-07

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

Efficient capture of CO2 over ordered micro-mesoporous hybrid carbon nanosphere

NASA Astrophysics Data System (ADS)

Chen, Changwei; Yu, Yanke; He, Chi; Wang, Li; Huang, Huang; Albilali, Reem; Cheng, Jie; Hao, Zhengping

2018-05-01

Four kinds of carbon-based adsorbents (micro-mesoporous hybrid carbon nanosphere and N-doped hollow carbon sphere with single-, double- or ruga-shell morphology) with different structural and textural properties were prepared and systematically studied in CO2 capture. All synthesized samples possess high specific surface area (828-910 m2 g-1), large pore volume (0.71-1.81 cm3 g-1), and different micropore contents varied from 2.1% to 46.4%. Amongst, the ordered micro-mesoporous carbon nanosphere (OM-CNS) exhibits the best adsorption performance with CO2 uptake as high as 3.01 mmol g-1 under conditions of 298 K and 1.0 bar, better than most of the reported CO2 adsorbents. The excellent CO2 adsorption capacity of OM-CNS can be reasonably attributed to the synergistic effect of ordered mesopore channels and abundant structural micropores which are beneficial for the diffusion and trapping of CO2 adsorbate. Moreover, the OM-CNS shows excellent CO2 trapping selectivity and superior stability and recyclability, which endow the OM-CNS as a promising and environmental-friendly adsorbent for CO2 capture and separation under practical conditions.

Noncompetitive and Competitive Adsorption of Heavy Metals in Sulfur-Functionalized Ordered Mesoporous Carbon.

PubMed

Saha, Dipendu; Barakat, Soukaina; Van Bramer, Scott E; Nelson, Karl A; Hensley, Dale K; Chen, Jihua

2016-12-14

In this work, sulfur-functionalized ordered mesoporous carbons were synthesized by activating the soft-templated mesoporous carbons with sulfur bearing salts that simultaneously enhanced the surface area and introduced sulfur functionalities onto the parent carbon surface. XPS analysis showed that sulfur content within the mesoporous carbons were between 8.2% and 12.9%. The sulfur functionalities include C-S, C═S, -COS, and SO x . SEM images confirmed the ordered mesoporosity within the material. The BET surface areas of the sulfur-functionalized ordered mesoporous carbons range from 837 to 2865 m 2 /g with total pore volume of 0.71-2.3 cm 3 /g. The carbon with highest sulfur functionality was examined for aqueous phase adsorption of mercury (as HgCl 2 ), lead (as Pb(NO 3 ) 2 ), cadmium (as CdCl 2 ), and nickel (as NiCl 2 ) ions in both noncompetitive and competitive mode. Under noncompetitive mode and at a pH greater than 7.0 the affinity of sulfur-functionalized carbons toward heavy metals were in the order of Hg > Pb > Cd > Ni. At lower pH, the adsorbent switched its affinity between Pb and Cd. In the noncompetitive mode, Hg and Pb adsorption showed a strong pH dependency whereas Cd and Ni adsorption did not demonstrate a significant influence of pH. The distribution coefficient for noncompetitive adsorption was in the range of 2448-4000 mL/g for Hg, 290-1990 mL/g for Pb, 550-560 mL/g for Cd, and 115-147 for Ni. The kinetics of adsorption suggested a pseudo-second-order model fits better than other models for all the metals. XPS analysis of metal-adsorption carbons suggested that 7-8% of the adsorbed Hg was converted to HgSO 4 , 14% and 2% of Pb was converted to PbSO 4 and PbS/PbO, respectively, and 5% Cd was converted to CdSO 4 . Ni was below the detection limit for XPS. Overall results suggested these carbon materials might be useful for the separation of heavy metals.

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

PubMed

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

2014-02-26

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

Study on the electrochemical properties of cubic ordered mesoporous carbon for supercapacitors

NASA Astrophysics Data System (ADS)

Lang, Jun-Wei; Yan, Xing-Bin; Yuan, Xiao-Yan; Yang, Jie; Xue, Qun-Ji

Highly ordered, three-dimensional (3D) cubic mesoporous carbon CMK-8 is prepared by a facile nanocasting approach using cubic mesoporous silica KIT-6 as starting template. Afterwards, in order to increase the active sites of surface electrochemical reactions and promote the wettability in aqueous electrolyte, a chemical surface modification is carried out on the CMK-8 by nitric acid treatment. Two electrodes are prepared from the CMK-8 and the acid-modified CMK-8 (H-CMK-8) and used as the active materials for supercapacitors. The unique 3D mesoporous network combined with high specific surface area makes the nano-channel surfaces of the CMK-8 carbon favorable for charging the electric double-layer, resulting in that the CMK-8 and the H-CMK-8 electrodes both show well supercapacitive properties. Furthermore, the specific capacitance of the CMK-8 can be further improved by acid treatment, so that the H-CMK-8 exhibits the largest specific capacitance of 246 F g -1 at a current density of 0.625 A g -1 in 2 M KOH electrolyte. Also, the two carbon electrodes both exhibit good cycling stability and lifetime. Therefore, based on the above investigations, such CMK-8 carbon, especially H-CMK-8 carbon can be a potential candidate for supercapacitors.

The enrichment of chlorogenic acid from Eucommia ulmoides leaves extract by mesoporous carbons.

PubMed

Qin, Guotong; Ma, Jing; Wei, Wei; Li, Jaja; Yue, Fangqing

2018-06-15

Herein, we report an efficient separation and enrichment method for chlorogenic acid from crude extracts of Eucommia ulmoides leaves using carbon adsorbents. The effects of the pore structure of the carbon adsorbents on the adsorption capacity were studied. Of the four adsorbents investigated, mesoporous carbon (MC3) showed the highest adsorption capacity (294 mg/g of carbon) for chlorogenic acid due to its high mesopore volume. The static adsorption of CGA on carbon can be accurately described using the Freundlich equation. The kinetics of adsorption follow a pseudo-second-order process. External mass transfer was the controlling step of the adsorption process. Dynamic adsorption on MC3 demonstrated that chlorogenic acid began to break through after 28 bed volumes of extract was loaded. This mesoporous carbon-treatment procedure is safe, economic and has the potential to be scaled up for commercial application. Copyright © 2018 Elsevier B.V. All rights reserved.

Direct fabrication of ordered mesoporous carbons with super-micropore/small mesopore using mixed triblock copolymers.

PubMed

Li, Peng; Song, Yan; Tang, Zhihong; Yang, Guangzhi; Yang, Junhe

2014-01-01

Ordered mesoporous carbons (OMCs) have been prepared by the strategy of evaporation-induced organic-organic self-assembly method by employing a mixture of amphiphilic triblock copolymers poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) (PEO-PPO-PEO) and reverse PPO-PEO-PPO as templates, with soluble in ethanol, low-molecular-weight phenolic resin as precursor, followed by carbonization. It has been found that the as prepared OMCs with porosity that combines super-micropore and small mesopore size distributed from 0.8 to 4 nm, which bridges the pore size from 2 to 3 nm and also for the diversification of the soft-templating synthesis of OMCs. Furthermore, the results showed that the OMCs obtained have mesophase transition from cylindrical p6 mm to centered rectangular c2 mm structure by simply tuning the ratio of PPO-PEO-PPO/PEO-PPO-PEO. Copyright © 2013 Elsevier Inc. All rights reserved.

One-pot synthesis of transition metal ion-chelating ordered mesoporous carbon/carbon nanotube composites for active and durable fuel cell catalysts

NASA Astrophysics Data System (ADS)

Dombrovskis, Johanna K.; Palmqvist, Anders E. C.

2017-07-01

Development of non-precious metal catalysts for the oxygen reduction reaction (ORR) in proton exchange membrane (PEM) fuel cells with high activity and durability and with optimal water management properties is of outmost technological importance and highly challenging. Here we study the possibilities offered through judicious selection of small molecular precursors used for the formation of ordered mesoporous carbon-based non-precious metal ORR catalysts. By combining two complementary precursors, we present a one-pot synthesis that leads to a composite material consisting of transition metal ion-chelating ordered mesoporous carbon and multi-walled carbon nanotubes (TM-OMC/CNT). The resulting composite materials show high specific surface areas and a carbon structure that exhibits graphitic signatures. The synthesis procedure allows for tuning of the carbon structure, the surface area, the pore volume and the ratio of the two components of the composite. The TM-OMC/CNT composites were processed into membrane electrode assemblies and evaluated in single cell fuel cell measurements where they showed a combination of good ORR activity and very high durability.

Facile Control of the Porous Structure of Larch-Derived Mesoporous Carbons via Self-Assembly for Supercapacitors

PubMed Central

Zhao, Xin; Li, Wei; Chen, Honglei; Wang, Shoujuan; Kong, Fangong; Liu, Shouxin

2017-01-01

Mesoporous carbons have been successfully synthesized via self-assembly using larch-based resins as precursors and triblock copolymers as soft templates. The porous structure of mesoporous carbons can be tailored by adjusting the ratio of hydrophilic/hydrophobic (EO/PO) units owing to interfacial curvature. Interestingly, the porous structures show a distinct change from vortex-like to worm-like pores, to stripe-like pores, and to ordered two-dimensional hexagonal pores as the ratio of hydrophilic/hydrophobic units increases, indicating the significant effect of EO/PO ratio on the porous structure. The mesoporous carbons as supercapacitor electrodes exhibit superior electrochemical capacitive performance and a high degree of reversibility after 2000 cycles for supercapacitors due to the well-defined mesoporosity of the carbon materials. Meanwhile, the superior carbon has a high specific capacitance of 107 F·g−1 in 6 M KOH at a current density of 10 A·g−1. PMID:29156641

Facile Control of the Porous Structure of Larch-Derived Mesoporous Carbons via Self-Assembly for Supercapacitors.

PubMed

Zhao, Xin; Li, Wei; Chen, Honglei; Wang, Shoujuan; Kong, Fangong; Liu, Shouxin

2017-11-20

Mesoporous carbons have been successfully synthesized via self-assembly using larch-based resins as precursors and triblock copolymers as soft templates. The porous structure of mesoporous carbons can be tailored by adjusting the ratio of hydrophilic/hydrophobic (EO/PO) units owing to interfacial curvature. Interestingly, the porous structures show a distinct change from vortex-like to worm-like pores, to stripe-like pores, and to ordered two-dimensional hexagonal pores as the ratio of hydrophilic/hydrophobic units increases, indicating the significant effect of EO/PO ratio on the porous structure. The mesoporous carbons as supercapacitor electrodes exhibit superior electrochemical capacitive performance and a high degree of reversibility after 2000 cycles for supercapacitors due to the well-defined mesoporosity of the carbon materials. Meanwhile, the superior carbon has a high specific capacitance of 107 F·g -1 in 6 M KOH at a current density of 10 A·g -1 .

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

NASA Astrophysics Data System (ADS)

Liou, Tzong-Horng

2012-07-01

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

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

PubMed

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

2014-07-01

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

Synthesis and Supercapacitor Performance of Polyaniline/Nitrogen-Doped Ordered Mesoporous Carbon Composites

NASA Astrophysics Data System (ADS)

Xie, Kangjun; Zhang, Manman; Yang, Yang; Zhao, Long; Qi, Wei

2018-05-01

The electrochemical property of ordered mesoporous carbon (OMC) can be changed significantly due to the incorporating of electron-donating heteroatoms into OMC. Here, we demonstrate the successful fabrication of nitrogen-doped ordered mesoporous carbon (NOMC) materials to be used as carbon substrates for loading polyaniline (PANI) by in situ polymerization. Compared with NOMC, the PANI/NOMC prepared with a different mass ratio of PANI and NOMC exhibits remarkably higher electrochemical specific capacitance. In a typical three-electrode configuration, the hybrid has a specific capacitance about 276.1 F/g at 0.2 A/g with a specific energy density about 38.4 Wh/kg. What is more, the energy density decreases very slowly with power density increasing, which is a different phenomenon from other reports. PANI/NOMC materials exhibit good rate performance and long cycle stability in alkaline electrolyte ( 80% after 5000 cycles). The fabrication of PANI/NOMC with enhanced electrochemical properties provides a feasible route for promoting its applications in supercapacitors.

Facile synthesis of highly stable and well-dispersed mesoporous ZrO(2)/carbon composites with high performance in oxidative dehydrogenation of ethylbenzene.

PubMed

Li, Qiang; Xu, Jie; Wu, Zhangxiong; Feng, Dan; Yang, Jianping; Wei, Jing; Wu, Qingling; Tu, Bo; Cao, Yong; Zhao, Dongyuan

2010-09-28

Highly ordered mesoporous ZrO(2)/carbon (FDU-15) composites have been synthesized via a facile evaporation induced triconstituent co-assembly (EISA) approach by using Pluronic F127 as a template and zirconium oxychloride octahydrate and resol as Zr and carbon sources. The synthesized mesoporous composites exhibit a highly ordered two-dimensional (2-D) hexagonal mesostructure with relatively high specific surface areas (up to 947 m(2) g(-1)), pore sizes around 3.8 nm and high pore volumes (up to 0.71 cm(3) g(-1)). The results clearly show that the crystalline zirconia nanoparticles (ca. 1.9-3.9 nm) are well-dispersed in amorphous matrices of the ordered mesoporous carbon FDU-15 materials, which construct the nanocomposites. The ordered mesostructures of the obtained ZrO(2)/FDU-15 composites can be well-retained even at the high pyrolysis temperature (up to 900 degrees C), suggesting a high thermal stability. The zirconia content of the ZrO(2)/FDU-15 composites can be tunable in a wide range (up to 47%). Moreover, the resultant mesoporous ZrO(2)/FDU-15 composites exhibit high catalytic activity in oxidative dehydrogenation (ODH) of ethylbenzene (EB) to styrene (ST), with high ethylbenzene conversion (59.6%) and styrene selectivity (90.4%), which is mainly attributed to the synergistic catalytic effect between the oxygen-containing groups located on the carbon pore walls and weakly basic sites of the nanocrystalline ZrO(2). Furthermore, the high specific surface areas and opening pore channels are also responsible for their high catalytic activity. Therefore, it is a very promising catalyst material in styrene production on an industrial scale.

Investigation of Free-Standing Plasmonic Mesoporous Ag/CMK-8-Nafion Composite Membrane for the Removal of Organic Pollutants with 254-nm UV Irradiation

NASA Astrophysics Data System (ADS)

Tseng, Chuan Ming; Chen, Hsin Liang; Lai, Sz Nian; Chen, Ming Shiung; Peng, Chien Jung; Li, Chia Jui; Hung, Wei Hsuan

2017-05-01

"Carbon-based material" has demonstrated a great potential on water purification due to its strong physical adsorption to organic pollutants in the water. Three-dimensional cubic ordered mesoporous carbon (CMK-8), one of the well-known ordered mesoporous carbons, was prepared by using nanocasting method with mesoporous silica (KIT-6) as the template. In this study, CMK-8 blended with Nafion polymer to form a free-standing mesoporous CMK-8-Nafion composite membrane. The synthesis of high crystallinity CMK-8 was characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). More than 80% methyl orange (MO) removal efficiency was observed under 254-nm UV irradiation after 120 min. Ninety-two percent recycling performance was remained after four recycling tests, which indicated a reliable servicing lifetime for the water purification. Furthermore, an additional layer of plasmonic silver nanoparticles (Ag NPs) was integrated into this CMK-8-Nafion membrane for higher pollutant removal efficiency, attributing from the generation of plasmon-resonance hot electrons from Ag NPs. A 4-in. CMK-8-Nafion composite membrane was also fabricated for the demonstration of potential large-scale utilization.

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

PubMed Central

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

2016-01-01

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

Rapid removal of bisphenol A on highly ordered mesoporous carbon.

PubMed

Sui, Qian; Huang, Jun; Liu, Yousong; Chang, Xiaofeng; Ji, Guangbin; Deng, Shubo; Xie, Tao; Yu, Gang

2011-01-01

Bisphenol A (BPA) is of global concern due to its disruption of endocrine systems and ubiquity in the aquatic environment. It is important, therefore, that efforts are made to remove it from the aqueous phase. A novel adsorbent, mesoporous carbon CMK-3, prepared from hexagonal SBA-15 mesoporous silica was studied for BPA removal from aqueous phase, and compared with conventional powdered activated carbon (PAC). Characterization of CMK-3 by transmission electron microscopy (TEM), X-ray diffraction, and nitrogen adsorption indicated that prepared CMK-3 had an ordered mesoporous structure with a high specific surface area of 920 m2/g and a pore-size of about 4.9 nm. The adsorption of BPA on CMK-3 followed a pseudo second-order kinetic model. The kinetic constant was 0.00049 g/(mg x min), much higher than the adsorption of BPA on PAC. The adsorption isotherm fitted slightly better with the Freundlich model than the Langmuir model, and adsorption capacity decreased as temperature increased from 10 to 40 degrees C. No significant influence of pH on adsorption was observed at pH 3 to 9; however, adsorption capacity decreased dramatically from pH 9 to 13.

Design, fabrication, and testing of nanostructured carbons and composites

NASA Astrophysics Data System (ADS)

Wang, Zhiyong

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

Preparation of nitrogen and sulfur co-doped ordered mesoporous carbon for enhanced microwave absorption performance

NASA Astrophysics Data System (ADS)

Yuan, Xiaoyan; Xue, Xingkun; Ma, Hailong; Guo, Shouwu; Cheng, Laifei

2017-09-01

Ordered mesoporous carbon nanomaterials (OMCs) co-doped with homogeneous nitrogen and sulfur heteroatoms were prepared by nanocasting with the pyrrole oligomer catalyzed by sulfuric acid as a precursor and ordered mesoporous silica SBA-15 as a hard-template. By multi-technique approach utilization, it was demonstrated that the N and S co-doped OMCs possessed high ordered mesoporous structures, large surface areas and homogeneous distribution of heteroatoms. As a microwave absorber, the as-prepared materials exhibited a minimum reflection loss (RL) of -32.5 dB at the thickness of 2.5 mm and an absorption bandwidth of 3.2 GHz (RL < -10 dB) in X-band (8.2-12.4 GHz). The good microwave absorption performance was mainly originated from the high electrical conductivity induced by the high surface activity and special structures. And microwave energy can be effectively attenuated through multiple reflections and absorptions in complex conductive network. The design strategy in this work would contribute to the production of a lightweight absorber, presenting a strong absorbency and a wide bandwidth in microwave frequency.

Surface-functionalized mesoporous carbon materials

DOEpatents

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

2016-02-02

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

Monolithic Gyroidal Mesoporous Mixed Titanium–Niobium Nitrides

PubMed Central

2015-01-01

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

Mesoporous carbon materials

DOEpatents

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

2014-09-09

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

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

PubMed

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

2012-07-01

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

High rate sodium ion battery anodes from block copolymer templated mesoporous nickel–cobalt carbonates and oxides

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

Bhaway, Sarang M.; Tangvijitsakul, Pattarasai; Lee, Jeongwoo

2015-09-16

Micelle-templated ordered mesoporous nickel–cobalt carbonates and oxides are fabricated using a metal nitrate–citric acid strategy, which avoids the hydrolysis and aging requirements associated with sol–gel chemistry. A series of mesoporous Ni xCo (3-x)(CO 3) y and Ni xCo (3-x)O 4 films with varying Ni–Co compositions and 14 ± 4 nm mesopores are fabricated with the same block copolymer template. AFM and GISAXS analysis indicates that the mesostructure is maintained through the formation of the carbonate and oxide, while GIXD profiles confirm formation of pure spinel phases of semi-crystalline Ni xCo (3-x)O 4. The micelle templated mesopores are interconnected and providemore » transport paths for the electrolyte to minimize the solid-state diffusion requirements associated with battery electrodes. These materials exhibit good performance as sodium ion battery anodes even at high current densities of 4 A g -1. Amongst the mixed-metal oxides, Ni 2CoO 4 exhibits the highest specific capacity of 239 mA h g -1 after galvanostatic cycling at a current density of 1 A g -1 for 10 cycles. We attribute the superior performance of Ni 2CoO 4 at high rates to the high surface area and short ion-diffusion paths of the nanoporous anode architecture, while the higher nickel content in the mixed metal oxide provides enhanced stability during oxide formation along with enhanced electronic conductivity, leading to improved cycling stability of the anode. This micelle template metal nitrate–citric acid method enables new possibilities for fabricating variety of ordered mesoporous mixed-metal carbonates and oxides that could be used in a wide range of applications.« less

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

PubMed

Wilgosz, Karolina; Chen, Xuecheng; Kierzek, Krzysztof; Machnikowski, Jacek; Kalenczuk, Ryszard J; Mijowska, Ewa

2012-05-29

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

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

NASA Astrophysics Data System (ADS)

Wilgosz, Karolina; Chen, Xuecheng; Kierzek, Krzysztof; Machnikowski, Jacek; Kalenczuk, Ryszard J.; Mijowska, Ewa

2012-05-01

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

Preparation and drug release behavior of temperature-responsive mesoporous carbons

NASA Astrophysics Data System (ADS)

Wang, Xiufang; Liu, Ping; Tian, Yong

2011-06-01

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

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

NASA Astrophysics Data System (ADS)

Kado, Yuya; Soneda, Yasushi; Yoshizawa, Noriko

2015-02-01

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

Tuning the Pore Geometry of Ordered Mesoporous Carbons for Enhanced Adsorption of Bisphenol-A

PubMed Central

Libbrecht, Wannes; Vandaele, Koen; De Buysser, Klaartje; Verberckmoes, An; Thybaut, Joris W.; Poelman, Hilde; De Clercq, Jeriffa; Van Der Voort, Pascal

2015-01-01

Mesoporous carbons were synthesized via both soft and hard template methods and compared to a commercial powder activated carbon (PAC) for the adsorption ability of bisphenol-A (BPA) from an aqueous solution. The commercial PAC had a BET-surface of 1027 m2/g with fine pores of 3 nm and less. The hard templated carbon (CMK-3) material had an even higher BET-surface of 1420 m2/g with an average pore size of 4 nm. The soft templated carbon (SMC) reached a BET-surface of 476 m2/g and a pore size of 7 nm. The maximum observed adsorption capacity (qmax) of CMK-3 was the highest with 474 mg/g, compared to 290 mg/g for PAC and 154 mg/g for SMC. The difference in adsorption capacities was attributed to the specific surface area and hydrophobicity of the adsorbent. The microporous PAC showed the slowest adsorption, while the ordered mesopores of SMC and CMK-3 enhanced the BPA diffusion into the adsorbent. This difference in adsorption kinetics is caused by the increase in pore diameter. However, CMK-3 with an open geometry consisting of interlinked nanorods allows for even faster intraparticle diffusion. PMID:28788023

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

PubMed Central

2012-01-01

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

Soft-Templating Synthesis of N-Doped Mesoporous Carbon Nanospheres for Enhanced Oxygen Reduction Reaction.

PubMed

Bayatsarmadi, Bita; Zheng, Yao; Jaroniec, Mietek; Qiao, Shi Zhang

2015-07-01

The development of ordered mesoporous carbon materials with controllable structures and improved physicochemical properties by doping heteroatoms such as nitrogen into the carbon framework has attracted a lot of attention, especially in relation to energy storage and conversion. Herein, a series of nitrogen-doped mesoporous carbon spheres (NMCs) was synthesized via a facile dual soft-templating procedure by tuning the nitrogen content and carbonization temperature. Various physical and (electro)chemical properties of the NMCs have been comprehensively investigated to pave the way for a feasible design of nitrogen-containing porous carbon materials. The optimized sample showed a favorable electrocatalytic activity as evidenced by a high kinetic current and positive onset potential for oxygen reduction reaction (ORR) due to its large surface area, high pore volume, good conductivity, and high nitrogen content, which make it a highly efficient ORR metal-free catalyst in alkaline solutions. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

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

Fulvio, Pasquale F; Mahurin, Shannon Mark; Mayes, Richard T

2012-01-01

Soft-templated phosphorylated mesoporous carbons with homogeneous distributions of phosphate groups were prepared by a 'one-pot' synthesis method using mixtures of phosphoric acid with hydrochloric, or nitric acids in the presence of Pluronic F127 triblock copolymer. Adjusting the various ratios of phosphoric acid used in these mixtures resulted in carbons with distinct adsorption, structural and surface acidity properties. The pore size distributions (PSDs) from nitrogen adsorption at -196 C showed that mesoporous carbons exhibit specific surface areas as high as 551 m{sup 2}/g and mesopores as large as 13 nm. Both structural ordering of the mesopores and the final phosphate contentsmore » 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.« less

Hierarchical Composites to Reduce N-Nitrosamines in Cigarette Smoke

PubMed Central

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

2015-01-01

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

Recent Trends on Electrochemical Sensors Based on Ordered Mesoporous Carbon

PubMed Central

Walcarius, Alain

2017-01-01

The past decade has seen an increasing number of extensive studies devoted to the exploitation of ordered mesoporous carbon (OMC) materials in electrochemistry, notably in the fields of energy and sensing. The present review summarizes the recent achievements made in field of electroanalysis using electrodes modified with such nanomaterials. On the basis of comprehensive tables, the interest in OMC for designing electrochemical sensors is illustrated through the various applications developed to date. They include voltammetric detection after preconcentration, electrocatalysis (intrinsically due to OMC or based on suitable catalysts deposited onto OMC), electrochemical biosensors, as well as electrochemiluminescence and potentiometric sensors. PMID:28800106

Zeolite-templated carbons - three-dimensional microporous graphene frameworks.

PubMed

Nishihara, H; Kyotani, T

2018-05-31

Zeolite-templated carbons (ZTCs) are ordered microporous carbons synthesized by using zeolite as a sacrificial template. Unlike well-known ordered mesoporous carbons obtained by using mesoporous silica templates, ZTCs consist of curved and single-layer graphene frameworks, thereby affording uniform micropore size (ca. 1.2 nm), developed microporosity (∼1.7 cm3 g-1), very high surface area (∼4000 m2 g-1), good compatibility with chemical modification, and remarkable softness/elasticity. Thus, ZTCs have been used in many applications such as hydrogen storage, methane storage, CO2 capture, liquid-phase adsorption, catalysts, electrochemical capacitors, batteries, and fuel cells. Herein, the relevant research studies are summarized, and the properties as well as the performances of ZTCs are compared with those of other materials including metal-organic frameworks, to elucidate the intrinsic advantages of ZTCs and their future development.

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

PubMed

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

2011-04-18

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

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

PubMed

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

2014-04-04

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.

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

NASA Astrophysics Data System (ADS)

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

2014-04-01

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

Study of CO2 adsorption capacity of mesoporous carbon and activated carbon modified by triethylenetetramine (TETA)

NASA Astrophysics Data System (ADS)

Sulistianti, I.; Krisnandi, Y. K.; Moenandar, I.

2017-04-01

Mesoporous carbon was synthesized by soft template method using phloroglucinol and formaldehyde as a carbon source; and Pluronic F-127 as a mesoporous template. The synthesized mesoporous carbon and commercial activated carbon were modified with triethylenetetramine (TETA) to increase CO2 adsorption capacity. Based on FTIR characterization, the synthesized mesoporous carbon and the activated carbon without modification process has similarity pattern. After the modification, both of them showed absorption peaks in the area around 1580 to 1650 cm-1 which is known as N-H bending vibration and absorption peaks in the area around 3150 to 3380 cm-1 which is known as N-H stretching vibration. The XRD results showed two peaks at 2θ = 24.21° and 2θ = 43.85°, according to JCPDS index No. 75-1621 those peak are the typical peaks for hexagonal graphite carbon. In BET analysis, the synthesized mesoporous carbon and activated carbon modified TETA have surface area, pore volume and pore diameter lower than without modification process. In carbon dioxide adsorption testing, the synthesized mesoporous carbon showed better performance than the commercial activated carbon for CO2 adsorption both without modification and by modification. The synthesized mesoporous carbon obtained CO2 adsorption of 9.916 mmol/g and the activated carbon of 3.84 mmol/g for on 3.5 hours of adsorption. It is three times better than activated carbon for adsorption of carbon dioxide. The modified mesoporous carbon has the best performance for adsorption of gas CO2 if compared by unmodified.

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

PubMed

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

2013-03-01

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

Zero-valent iron particles embedded on the mesoporous silica-carbon for chromium (VI) removal from aqueous solution

NASA Astrophysics Data System (ADS)

Xiong, Kun; Gao, Yuan; Zhou, Lin; Zhang, Xianming

2016-09-01

Nanoscale zero-valent iron (nZVI) particles were embedded on the walls of mesoporous silica-carbon (MSC) under the conditions of high-temperature carbonization and reduction and used to remove chromium (VI) from aqueous solution. The structure and textural properties of nZVI-MSC were characterized by the powder X-ray diffraction, transmission electron microscopy and N2 adsorption and desorption. The results show that nZVI-MSC has highly ordered mesoporous structure and large surface area, indistinguishable with that of MSC. Compared with the support MSC and iron particles supported on the activated carbon (nZVI/AC), nZVI-MSC exhibited much higher Cr(VI) removal efficiency with about 98 %. The removal process obeys a pseudo first-order model. Such excellent performance of nZVI-MSC could be ascribed to the large surface and iron particles embedded on the walls of the MSC, forming an intimate contact with the MSC. It is proposed that this feature might create certain micro-electrode on the interface of iron particles and MSC, which prevented the formation of metal oxide on the surface and provided fresh Fe surface for Cr(VI) removal.

Synthesis of Mesoporous Metal Oxides by Structure Replication: Thermal Analysis of Metal Nitrates in Porous Carbon Matrices

PubMed Central

Weinberger, Christian; Roggenbuck, Jan; Hanss, Jan; Tiemann, Michael

2015-01-01

A variety of metal nitrates were filled into the pores of an ordered mesoporous CMK-3 carbon matrix by solution-based impregnation. Thermal conversion of the metal nitrates into the respective metal oxides, and subsequent removal of the carbon matrix by thermal combustion, provides a versatile means to prepare mesoporous metal oxides (so-called nanocasting). This study aims to monitor the thermally induced processes by thermogravimetric analysis (TGA), coupled with mass ion detection (MS). The highly dispersed metal nitrates in the pores of the carbon matrix tend to react to the respective metal oxides at lower temperature than reported in the literature for pure, i.e., carbon-free, metal nitrates. The subsequent thermal combustion of the CMK-3 carbon matrix also occurs at lower temperature, which is explained by a catalytic effect of the metal oxides present in the pores. This catalytic effect is particularly strong for oxides of redox active metals, such as transition group VII and VIII metals (Mn, Fe, Co, Ni), Cu, and Ce. PMID:28347073

[Study on absorbing volatile oil with mesoporous carbon].

PubMed

Yan, Hong-mei; Jia, Xiao-bin; Zhang, Zhen-hai; Sun, E; Yang Nan

2014-11-01

Clove oil and turmeric oil were absorbed by mesoporous carbon. The absorption ratio of mesoporous carbon to volatile oil was optimized with the eugenol yield and curcumol yield as criteria Curing powder was characterized by scanning electron microscopy (SEM) and differential scanning calorietry (DSC). The effects of mesoporous carbon on dissolution in vitro and thermal stability of active components were studied. They reached high adsorption rate when the absorption ratio of mesoporous carbon to volatile oil was 1:1. When volatile oil was absorbed, dissolution rate of active components had a little improvement and their thermal stability improved after volatile oil was absorbed by the loss rate decreasing more than 50%. Absorbing herbal volatile oil with mesoporous carbon deserves further studying.

Loading amorphous Asarone in mesoporous silica SBA-15 through supercritical carbon dioxide technology to enhance dissolution and bioavailability.

PubMed

Zhang, Zhengzan; Quan, Guilan; Wu, Qiaoli; Zhou, Chan; Li, Feng; Bai, Xuequn; Li, Ge; Pan, Xin; Wu, Chuanbin

2015-05-01

The aim of this study was to load amorphous hydrophobic drug into ordered mesoporous silica (SBA-15) by supercritical carbon dioxide technology in order to improve the dissolution and bioavailability of the drug. Asarone was selected as a model drug due to its lipophilic character and poor bioavailability. In vitro dissolution and in vivo bioavailability of the obtained Asarone-SBA-15 were significantly improved as compared to the micronized crystalline drug. This study offers an effective, safe, and environmentally benign means of solving the problems relating to the solubility and bioavailability of hydrophobic molecules. Copyright © 2015 Elsevier B.V. All rights reserved.

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

PubMed

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

2014-01-01

Nanocomposite to achieve ultrafast immunoassay: a new synergistically integrated nanocomposite consisting of magnetic and platinum nanoparticles, simultaneously entrapped in mesoporous carbon, is developed as a promising enzyme mimetic candidate to achieve ultrafast colorimetric immunoassays. Using new assay system, clinically important target molecules, such as human epidermal growth factor receptor 2 (HER2) and diarrhea-causing rotavirus, can be detected in only 3 min at room temperature with high specificity and sensitivity. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

N, P-codoped Mesoporous Carbon Supported PtCox Nanoparticles and Their Superior Electrochemical toward Methanol Oxidation

NASA Astrophysics Data System (ADS)

Cui, Hangjun; Li, Yueming; Liu, Shimin

2018-03-01

In this report, a novel strategy by using the N, P co-doped mesoporous carbon structure as catalyst support to enhance the electrochemical catalytic activity of Pt-based catalysts is proposed. The as-synthesized PtCox@N, P-doped mesoporous carbon nanocomposties have been studied as an anode catalyst toward methanol oxidation, exhibiting greatly improved electrochemical activity and stability compared with Pt@mesoporous carbon. The synergistic effects of N, P dual-doping and porous carbon structure help to achieve better electron transport at the electrode surface, which eventually leads to greatly enhanced catalytic activity compared to the pristine Pt/mesoporous carbon.…

Effect of ordered mesoporous carbon contact layer on the sensing performance of sputtered RuO2 thin film pH sensor.

PubMed

Lonsdale, W; Maurya, D K; Wajrak, M; Alameh, K

2017-03-01

The effect of contact layer on the pH sensing performance of a sputtered RuO 2 thin film pH sensor is investigated. The response of pH sensors employing RuO 2 thin film electrodes on screen-printed Pt, carbon and ordered mesoporous carbon (OMC) contact layers are measured over a pH range from 4 to 10. Working electrodes with OMC contact layer are found to have Nernstian pH sensitivity (-58.4mV/pH), low short-term drift rate (5.0mV/h), low hysteresis values (1.13mV) and fast reaction times (30s), after only 1h of conditioning. A pH sensor constructed with OMC carbon contact layer displays improved sensing performance compared to Pt and carbon-based counterparts, making this electrode more attractive for applications requiring highly-accurate pH sensing with reduced conditioning time. Copyright © 2016 Elsevier B.V. All rights reserved.

Soft-Template-Synthesized Mesoporous Carbon for Oral Drug Delivery

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

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

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

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

PubMed Central

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

2013-01-01

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

Ge/GeO2-Ordered Mesoporous Carbon Nanocomposite for Rechargeable Lithium-Ion Batteries with a Long-Term Cycling Performance.

PubMed

Zeng, Lingxing; Huang, Xiaoxia; Chen, Xi; Zheng, Cheng; Qian, Qingrong; Chen, Qinghua; Wei, Mingdeng

2016-01-13

Germanium-based nanostructures are receiving intense interest in lithium-ion batteries because they have ultrahigh lithium ion storage ability. However, the Germanium-based anodes undergo the considerably large volume change during the charge/discharge processes, leading to a fast capacity fade. In the present work, a Ge/GeO2-ordered mesoporous carbon (Ge/GeO2-OMC) nanocomposite was successfully fabricated via a facile nanocasting route by using mesoporous carbon as a nanoreactor, and was then used as an anode for lithium-ion batteries. Benefited from its unique three-dimensional "meso-nano" structure, the Ge/GeO2-OMC nanocomposite exhibited large reversible capacity, excellent long-time cycling stability and high rate performance. For instance, a large reversible capacity of 1018 mA h g(-1) was obtained after 100 cycles at a current density of 0.1 A g(-1), which might be attributed to the unique structure of the Ge/GeO2-OMC nanocomposite. In addition, a reversible capacity of 492 mA h g(-1) can be retained when cycled to 500 cycles at a current density of 1 A g(-1).

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

NASA Astrophysics Data System (ADS)

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

2014-06-01

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

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

DOE PAGES

Nelson, Kimberly M.; Mahurin, Shannon Mark; Mayes, Richard T.; ...

2015-10-09

This paper presents a soft templating approach for mesoporous carbon using the polyphenolic heterogeneous biomass, chestnut tannin, as the carbon precursor. By varying synthesis parameters such as tannin:surfactant ratio, cross-linker, reaction time and acid catalyst, the pore structure could be controllably modulated from lamellar to a more ordered hexagonal array. Carbonization at 600 °C under nitrogen produced a bimodal micro-mesoporous carbonaceous material exhibiting enhanced hydrogen bonding with the soft template, similar to that shown by soft-templating of phenolic-formaldehyde resins, allowing for a tailorable pore size. By utilizing the acidic nature of chestnut tannin (i.e. gallic and ellagic acid), hexagonal-type mesostructuresmore » were formed without the use of an acid catalyst. The porous carbon materials were activated with ammonia to increase the available surface area and incorporate nitrogen-containing functionality which led to a maximum CO 2 adsorption capacity at 1 bar of 3.44 mmol/g and 2.27 mmol/g at 0 °C and 25 °C, respectively. The ammonia-activated carbon exhibited multiple peaks in the adsorption energy distribution which indicates heterogeneity of adsorption sites for CO 2 capture.« less

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

NASA Astrophysics Data System (ADS)

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

2015-09-01

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

Mesoporous carbon nanomaterials in drug delivery and biomedical application.

PubMed

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

2017-01-01

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

Nitrogen-doped ordered mesoporous carbon with a high surface area, synthesized through organic-inorganic coassembly, and its application in supercapacitors.

PubMed

Song, Yanfang; Li, Li; Wang, Yonggang; Wang, Congxiao; Guo, Zaipin; Xia, Yongyao

2014-07-21

A new nitrogen-doped ordered mesoporous carbon (N-doped OMC) is synthesized by using an organic-inorganic coassembly method, in which resol is used as the carbon precursor, dicyandiamide as the nitrogen precursor, silicate oligomers as the inorganic precursors, and F127 as the soft template. The N-doped OMC possesses a surface area as high as 1374 m(2)  g(-1) and a large pore size of 7.4 nm. As an electrode material for supercapacitors, the obtained carbon exhibits excellent cycling stability and delivers a reversible specific capacitance as high as 308 F g(-1) in 1 mol L(-1) H(2)SO(4) aqueous electrolyte, of which 58 % of the capacity is due to pseudo-capacitance. The large specific capacitance is attributed to proper pore size distributions, large surface area, and high nitrogen content. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A three-dimensional ordered mesoporous carbon/carbon nanotubes nanocomposites for supercapacitors

NASA Astrophysics Data System (ADS)

Zhu, Zhengju; Hu, Yanjie; Jiang, Hao; Li, Chunzhong

2014-01-01

A three-dimensional ordered mesoporous carbon (OMC)/carbon nanotubes (CNTs) nanocomposite is prepared via a two-step procedure. Firstly, OMC is synthesized through a co-assembly strategy associated with the incorporation of Ni nanoparticles. Then Ni nanoparticles are used as catalyst for the growth of CNTs. The introduction of CNTs into OMC can construct a 3D conductive network, greatly improving the rate performance of the nanocomposites. The nanocomposite with optimal CNTs content, when applied as supercapacitor electrodes, exhibits a high specific capacitance (338.1 F g-1 at 1 A g-1), excellent rate capability (130.2 F g-1 at 50 A g-1) and high cycling stability (91.6% capacity retention after 4000 cycles) in 6 M KOH aqueous solution. Such intriguing electrochemical performance is mainly attributed to the synergistic effects between OMC and CNTs. It is reckoned that the present 3D OMC/CNTs nanocomposite can serve as a promising electrode material for supercapacitors.

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

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

McDowell, Rocklan; Dutech, Guy

2014-09-01

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

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

PubMed

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

2014-06-15

Sixteen mesoporous carbon adsorbents were synthesized by varying the ratio of soft to hard templates in order to optimize the pore textural properties of these adsorbents. The mesoporous carbon adsorbents have a high BET specific surface area (1590.3-2193.5 m(2)/g), large pore volume (1.72-2.56 cm(3)/g), and uniform pore size distribution with a median pore diameter ranging from 3.51 nm to 4.52 nm. It was observed that pore textural properties of the carbon adsorbents critically depend on the molar ratio of carbon sources to templates, and the hard template plays a more important role than the soft template in manipulating the pore textures. Adsorption isotherms of berberine hydrochloride at 303 K were measured to evaluate the adsorption efficacy of these adsorbents. The adsorption of berberine hydrochloride from aqueous solutions on the sixteen mesoporous carbon adsorbents synthesized in this work is very efficient, and the adsorption equilibrium capacities on all samples are more than double the adsorption capacities of berberine hydrochloride of the benchmark adsorbents (polymer resins and spherical activated carbons) at similar conditions. It was observed from the adsorption experiments that the equilibrium adsorption amounts of berberine hydrochloride are strongly correlated with the BET specific surface area and pore volume of the adsorbents. The adsorbent with the highest BET of 2193.5 m(2)/g displayed the largest adsorption capacity of 574 mg/g at an equilibrium concentration of 0.10mg/mL of berberine hydrochloride in an aqueous solution. Copyright © 2014 Elsevier Inc. All rights reserved.

Synthesis of Nitrogen-Doped Mesoporous Carbon for the Catalytic Oxidation of Ethylbenzene

NASA Astrophysics Data System (ADS)

Wang, Ruicong; Yu, Yifeng; Zhang, Yue; Lv, Haijun; Chen, Aibing

2017-06-01

Nitrogen-doped ordered mesoporous carbon (NOMC) was fabricated via a simple hard-template method by functionalized ionic liquids as carbon and nitrogen source, SBA-15 as a hard-template. The obtained NOMC materials have a high nitrogen content of 5.55 %, a high surface area of 446.2 m2 g-1, and an excellent performance in catalysing oxidation of ethylbenzene. The conversion rate of ethylbenzene can be up to 84.5% and the yield of acetophenone can be up to 69.9%, the results indicated that the NOMC materials have a faster catalytic rate and a higher production of acetophenone than catalyst-free and CMK-3, due to their uniform pore size, high surface area and rich active sites in the carbon pore walls.

Tuneable porous carbonaceous materials from renewable resources.

PubMed

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

2009-12-01

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

Mesoporous magnetic activated carbon: Effect of preparation route on texture and surface properties and on effect for Reactive Black 5 adsorption.

NASA Astrophysics Data System (ADS)

Giannakoudakis, Dimitrios; Saroyan, Hayarpi; Lazaridis, Nikolaos; Deliyanni, Eleni

2016-04-01

Mesoporous magnetic activated carbon: Effect of preparation route on texture and surface properties and on effect for Reactive Black 5 adsorption. Dimitrios Giannakoudakis1, Hayarpi Saroyan2, Nikolaos Lazaridis2, Eleni Deliyanni2 1 City College of New York, Chemistry Department, 160 Convent Avenue, New York, United States 2 Laboratory of General and oInorganic Chemical Technology, Department of Chemistry, Aristotle University of Thessaloniki, GR-541 24 Thessaloniki, Greece In this study, the effect of preparation route of a mesoporous magnetic activated carbon on Reactive Black 5 (RB5) adsorption was investigated. The synthesis of the magnetic activated carbon was achieved both with (i) impregnation method (Bmi), and (ii) co-precipitation with two precipitation agents: NaOH (Bm) and NH4OH (Bma). After synthesis, the full characterization with various techniques (SEM, FTIR, XRD, DTA, DTG, VSM) was achieved in order to testify the effect of the preparation route on its textural and surface properties. It was shown that after the precipitation method the prepared carbon presented a collapsed texture and small magnetic properties. Effects of initial solution pH, effect of temperature, adsorption isotherms and kinetics were investigated in order to conclude about the aforementioned effect of the preparation method on dye adsorption performance of the magnetic carbons. The adsorption evaluation of the magnetic activated carbon presented higher adsorption capacity of Bmi carbon (350 mg/g) and lower of Bm (150 mg/g). Equilibrium experiments are also performed studying the effect of contact time (pseudo-first and -second order equations) and temperature (isotherms at 25, 45 and 65 °C fitted to Langmuir and Freundlich model). A full thermodynamic evaluation was carried out, calculating the parameters of enthalpy, free energy and entropy (ΔHο, ΔGο and ΔSο). The characterization with various techniques revealed the possible interactions/forces of dye-composite system.

Mesoporous carbon materials

DOEpatents

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

2012-02-14

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

Mesoporous carbon materials

DOEpatents

Dai, Sheng; Wang, Xiqing

2013-08-20

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

Solid-state synthesis of ordered mesoporous carbon catalysts via a mechanochemical assembly through coordination cross-linking

PubMed Central

Zhang, Pengfei; Wang, Li; Yang, Shize; Schott, Jennifer A.; Liu, Xiaofei; Mahurin, Shannon M.; Huang, Caili; Zhang, Yu; Fulvio, Pasquale F.; Chisholm, Matthew F.; Dai, Sheng

2017-01-01

Ordered mesoporous carbons (OMCs) have demonstrated great potential in catalysis, and as supercapacitors and adsorbents. Since the introduction of the organic–organic self-assembly approach in 2004/2005 until now, the direct synthesis of OMCs is still limited to the wet processing of phenol-formaldehyde polycondensation, which involves soluble toxic precursors, and acid or alkali catalysts, and requires multiple synthesis steps, thus restricting the widespread application of OMCs. Herein, we report a simple, general, scalable and sustainable solid-state synthesis of OMCs and nickel OMCs with uniform and tunable mesopores (∼4–10 nm), large pore volumes (up to 0.96 cm3 g−1) and high-surface areas exceeding 1,000 m2 g−1, based on a mechanochemical assembly between polyphenol-metal complexes and triblock co-polymers. Nickel nanoparticles (∼5.40 nm) confined in the cylindrical nanochannels show great thermal stability at 600 °C. Moreover, the nickel OMCs offer exceptional activity in the hydrogenation of bulky molecules (∼2 nm). PMID:28452357

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

NASA Astrophysics Data System (ADS)

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

2012-11-01

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.

Hierarchical porous carbon aerogel derived from bagasse for high performance supercapacitor electrode.

PubMed

Hao, Pin; Zhao, Zhenhuan; Tian, Jian; Li, Haidong; Sang, Yuanhua; Yu, Guangwei; Cai, Huaqiang; Liu, Hong; Wong, C P; Umar, Ahmad

2014-10-21

Renewable, cost-effective and eco-friendly electrode materials have attracted much attention in the energy conversion and storage fields. Bagasse, the waste product from sugarcane that mainly contains cellulose derivatives, can be a promising candidate to manufacture supercapacitor electrode materials. This study demonstrates the fabrication and characterization of highly porous carbon aerogels by using bagasse as a raw material. Macro and mesoporous carbon was first prepared by carbonizing the freeze-dried bagasse aerogel; consequently, microporous structure was created on the walls of the mesoporous carbon by chemical activation. Interestingly, it was observed that the specific surface area, the pore size and distribution of the hierarchical porous carbon were affected by the activation temperature. In order to evaluate the ability of the hierarchical porous carbon towards the supercapacitor electrode performance, solid state symmetric supercapacitors were assembled, and a comparable high specific capacitance of 142.1 F g(-1) at a discharge current density of 0.5 A g(-1) was demonstrated. The fabricated solid state supercapacitor displayed excellent capacitance retention of 93.9% over 5000 cycles. The high energy storage ability of the hierarchical porous carbon was attributed to the specially designed pore structures, i.e., co-existence of the micropores and mesopores. This research has demonstrated that utilization of sustainable biopolymers as the raw materials for high performance supercapacitor electrode materials is an effective way to fabricate low-cost energy storage devices.

Carbon dioxide capture by activated methyl diethanol amine impregnated mesoporous carbon

NASA Astrophysics Data System (ADS)

Ardhyarini, N.; Krisnandi, Y. K.

2017-07-01

Activated Methyl Diethanol Amine (aMDEA) were impregnated onto the surface of the mesoporous carbon to increase carbon dioxide (CO2) adsorption capacity. The mesoporous carbon was synthesized through soft template method with phloroglucinol as carbon precursor and triblock copolymer (Pluronic F127) as structure directing agent. These activated MDEA impregnated mesoporous carbon (aMDEA-MC) were characterized using various solid characterization techniques. CO2 adsorption was investigated using autoclaved-reactor in the batch system. The FTIR spectrum of aMDEA-MC had absorption peaks at 3395 cm-1 and 1031 cm-1 which are characteristic for O-H stretch and amine C-N stretch in MDEA. The elemental analyzer showed that nitrogen content on the mesoporous carbon increased after impregnation by 23 wt.%. The BET surface area and total pore volume of mesoporous carbon decreased after impregnation, 43 wt.% and 50 wt.%, respectively. The maximum CO2 adsorption capacity of aMDEA43-MC was 2.63 mmol/g (298 K, 5 psi and pure CO2). This is 64 % and 35 % higher compared to the CO2 adsorption capacity of the starting MC and also commercially available activated carbon with higher surface area. All the results suggest that MDEA-MC is a promising adsorbent for CO2 capture.

The composite capacitive behaviors of the N and S dual doped ordered mesoporous carbon with ultrahigh doping level

NASA Astrophysics Data System (ADS)

Zhang, Deyi; Lei, Longyan; Shang, Yonghua; Wang, Kunjie; Wang, Yi

2016-01-01

Heteroatoms doping provides a promising strategy for improving the energy density of supercapacitors based on the carbon electrodes. In this paper, we present a N and S dual doped ordered mesoporous carbon with ultrahigh doping level using dimethylglyoxime as pristine precursor. The N doping content of the reported materials varies from 6.6 to 15.6 at.% dependent on the carbonization temperature, and the S doping content varies from 0.46 to 1.01 at.%. Due to the ultrahigh heteroatoms doping content, the reported materials exhibit pronounced pseudo-capacitance. Meanwhile, the reported materials exhibit high surface areas (640⿿869 m2 g⿿1), large pore volume (0.71⿿1.08 cm2 g⿿1) and ordered pore structure. The outstanding textual properties endow the reported materials excellent electrical double-layer capacitance (EDLC). By effectively combining the pseudo-capacitance with EDLC, the reported materials exhibit a surprising energy storage/relax capacity with the highest specific capacitance of 565 F g⿿1, which value is 3.3 times higher than that of pristine CMK-3, and can compete against some conventional pseudo-capacitance materials.

Mesoporous activated carbon from corn stalk core for lithium ion batteries

NASA Astrophysics Data System (ADS)

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

2018-04-01

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

Equilibrium, kinetic and thermodynamic studies for adsorption of BTEX onto Ordered Mesoporous Carbon (OMC).

PubMed

Konggidinata, Mas Iwan; Chao, Bing; Lian, Qiyu; Subramaniam, Ramalingam; Zappi, Mark; Gang, Daniel Dianchen

2017-08-15

Chemical and petrochemical industries produce substantial amounts of wastewater everyday. This wastewater contains organic pollutants such as benzene, toluene, ethylbenzene and xylenes (BTEX) that are toxic to human and aquatic life. Ordered Mesoporous Carbon (OMC), the adsorbent that possesses the characteristics of an ideal adsorbent was investigated to understand its properties and suitability for BTEX removal. Adsorption isotherms, adsorption kinetics, the effects of initial BTEX concentrations and temperatures on the adsorption process were studied. The OMCs were characterized using surface area and pore size analyzer, transmission electron microscopy (TEM), elemental analysis, thermogravimetric analysis (TGA) and fourier transform infrared spectroscopy (FTIR). The results suggested that the Langmuir Isotherm and Pseudo-Second-Order Models described the experimental data well. The thermodynamic parameters, Gibbs free energy (ΔG°), the enthalpy change (ΔH°) and the entropy change (ΔS°) of adsorption indicated that the adsorption processes were physical, endothermic, and spontaneous. In addition, OMC had 27% higher overall adsorption capacities compared to granular activated carbon (GAC). Copyright © 2017 Elsevier B.V. All rights reserved.

Report on Carbon Nano Material Workshop: Challenges and Opportunities

DTIC Science & Technology

2013-01-22

trolyte fuel cells ( PEMFCs ) utilize the ability of the catalysts to initiate and maintain the oxygen reduction reaction on the cathode and the fuel...oxidation reaction on the anode. In order to increase the efficiency of the PEMFC catalysts, high-surface-area mesoporous carbons, carbon blacks, carbon...mechanical and thermal properties derived from a three-dimensional intercon- nected nanonetwork structure. The exceptional properties of CAs for PEMFC

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

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

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

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

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

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

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

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

Quantitative atomic-scale structure characterization of ordered mesoporous carbon materials by solid state NMR

DOE PAGES

Wang, Zhuoran; Opembe, Naftali; Kobayashi, Takeshi; ...

2018-02-03

In this study, solid-state (SS)NMR techniques were applied to characterize the atomic-scale structures of ordered mesoporous carbon (OMC) materials prepared using Pluronic F127 as template with resorcinol and formaldehyde as polymerizing precursors. A rigorous quantitative analysis was developed using a combination of 13C SSNMR spectra acquired with direct polarization and cross polarization on natural abundant and selectively 13C-enriched series of samples pyrolyzed at various temperatures. These experiments identified and counted the key functional groups present in the OMCs at various stages of preparation and thermal treatment. Lastly, the chemical evolution of molecular networks, the average sizes of aromatic clusters andmore » the extended molecular structures of OMCs were then inferred by coupling this information with the elemental analysis results.« less

Quantitative atomic-scale structure characterization of ordered mesoporous carbon materials by solid state NMR

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

Wang, Zhuoran; Opembe, Naftali; Kobayashi, Takeshi

In this study, solid-state (SS)NMR techniques were applied to characterize the atomic-scale structures of ordered mesoporous carbon (OMC) materials prepared using Pluronic F127 as template with resorcinol and formaldehyde as polymerizing precursors. A rigorous quantitative analysis was developed using a combination of 13C SSNMR spectra acquired with direct polarization and cross polarization on natural abundant and selectively 13C-enriched series of samples pyrolyzed at various temperatures. These experiments identified and counted the key functional groups present in the OMCs at various stages of preparation and thermal treatment. Lastly, the chemical evolution of molecular networks, the average sizes of aromatic clusters andmore » the extended molecular structures of OMCs were then inferred by coupling this information with the elemental analysis results.« less

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

NASA Astrophysics Data System (ADS)

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

2014-10-01

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

Fabrication and textural characterization of nanoporous carbon electrodes embedded with CuO nanoparticles for supercapacitors.

PubMed

Prasad, Kumaresa P S; Dhawale, Dattatray S; Sivakumar, Thiripuranthagan; Aldeyab, Salem S; Zaidi, Javaid S M; Ariga, Katsuhiko; Vinu, Ajayan

2011-08-01

We introduce a novel strategy of fabricating nanoporous carbons loaded with different amounts of CuO nanoparticles via a hard templating approach, using copper-containing mesoporous silica as the template and sucrose as the carbon source. The nature and dispersion of the CuO nanoparticles on the surface of the nanoporous carbons were investigated by x-ray diffraction (XRD), high-resolution scanning electron microscopy (HRSEM) and high-resolution transmission electron microscopy (HRTEM). XRD results reveal that nanoporous carbons with embedded CuO nanoparticles exhibit a well-ordered mesoporous structure, whereas the nitrogen adsorption measurements indicate the presence of excellent textural characteristics such as high surface area, large pore volume and uniform pore size distribution. The amount of CuO nanoparticles in the nanochannels of the nanoporous carbon could be controlled by simply varying the Si/Cu molar ratio of the mesoporous silica template. Morphological characterization by SEM and TEM reveals that high-quality CuO nanoparticles are distributed homogeneously within the nanoporous carbon framework. The supercapacitance behavior of the CuO-loaded nanoporous carbons was investigated. The material with a small amount of CuO in the mesochannels and high surface area affords a maximum specific capacitance of 300 F g -1 at a 20 mV s -1 scan rate in an aqueous electrolyte solution. A supercapacitor containing the CuO-loaded nanoporous carbon is highly stable and exhibits a long cycle life with 91% specific capacitance retained after 1000 cycles.

Fabrication and textural characterization of nanoporous carbon electrodes embedded with CuO nanoparticles for supercapacitors

NASA Astrophysics Data System (ADS)

Prasad, Kumaresa P. S.; Dhawale, Dattatray S.; Sivakumar, Thiripuranthagan; Aldeyab, Salem S.; Zaidi, Javaid S. M.; Ariga, Katsuhiko; Vinu, Ajayan

2011-08-01

We introduce a novel strategy of fabricating nanoporous carbons loaded with different amounts of CuO nanoparticles via a hard templating approach, using copper-containing mesoporous silica as the template and sucrose as the carbon source. The nature and dispersion of the CuO nanoparticles on the surface of the nanoporous carbons were investigated by x-ray diffraction (XRD), high-resolution scanning electron microscopy (HRSEM) and high-resolution transmission electron microscopy (HRTEM). XRD results reveal that nanoporous carbons with embedded CuO nanoparticles exhibit a well-ordered mesoporous structure, whereas the nitrogen adsorption measurements indicate the presence of excellent textural characteristics such as high surface area, large pore volume and uniform pore size distribution. The amount of CuO nanoparticles in the nanochannels of the nanoporous carbon could be controlled by simply varying the Si/Cu molar ratio of the mesoporous silica template. Morphological characterization by SEM and TEM reveals that high-quality CuO nanoparticles are distributed homogeneously within the nanoporous carbon framework. The supercapacitance behavior of the CuO-loaded nanoporous carbons was investigated. The material with a small amount of CuO in the mesochannels and high surface area affords a maximum specific capacitance of 300 F g-1 at a 20 mV s-1 scan rate in an aqueous electrolyte solution. A supercapacitor containing the CuO-loaded nanoporous carbon is highly stable and exhibits a long cycle life with 91% specific capacitance retained after 1000 cycles.

Fabrication and textural characterization of nanoporous carbon electrodes embedded with CuO nanoparticles for supercapacitors

PubMed Central

Prasad, Kumaresa P S; Dhawale, Dattatray S; Sivakumar, Thiripuranthagan; Aldeyab, Salem S; Zaidi, Javaid S M; Ariga, Katsuhiko; Vinu, Ajayan

2011-01-01

We introduce a novel strategy of fabricating nanoporous carbons loaded with different amounts of CuO nanoparticles via a hard templating approach, using copper-containing mesoporous silica as the template and sucrose as the carbon source. The nature and dispersion of the CuO nanoparticles on the surface of the nanoporous carbons were investigated by x-ray diffraction (XRD), high-resolution scanning electron microscopy (HRSEM) and high-resolution transmission electron microscopy (HRTEM). XRD results reveal that nanoporous carbons with embedded CuO nanoparticles exhibit a well-ordered mesoporous structure, whereas the nitrogen adsorption measurements indicate the presence of excellent textural characteristics such as high surface area, large pore volume and uniform pore size distribution. The amount of CuO nanoparticles in the nanochannels of the nanoporous carbon could be controlled by simply varying the Si/Cu molar ratio of the mesoporous silica template. Morphological characterization by SEM and TEM reveals that high-quality CuO nanoparticles are distributed homogeneously within the nanoporous carbon framework. The supercapacitance behavior of the CuO-loaded nanoporous carbons was investigated. The material with a small amount of CuO in the mesochannels and high surface area affords a maximum specific capacitance of 300 F g-1 at a 20 mV s-1 scan rate in an aqueous electrolyte solution. A supercapacitor containing the CuO-loaded nanoporous carbon is highly stable and exhibits a long cycle life with 91% specific capacitance retained after 1000 cycles. PMID:27877410

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

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

Shin, Yongsoon; Wang, Chong M.; Engelhard, Mark H.

2009-07-01

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

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

PubMed

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

2013-11-28

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

Mesoporous carbon synthesized from different pore sizes of SBA-15 for high density electrode supercapacitor application

NASA Astrophysics Data System (ADS)

Jamil, Farinaa Md; Sulaiman, Mohd Ali; Ibrahim, Suhaina Mohd; Masrom, Abdul Kadir; Yahya, Muhd Zu Azhan

2017-12-01

A series of mesoporous carbon sample was synthesized using silica template, SBA-15 with two different pore sizes. Impregnation method was applied using glucose as a precursor for converting it into carbon. An appropriate carbonization and silica removal process were carried out to produce a series of mesoporous carbon with different pore sizes and surface areas. Mesoporous carbon sample was then assembled as electrode and its performance was tested using cyclic voltammetry and impedance spectroscopy to study the effect of ion transportation into several pore sizes on electric double layer capacitor (EDLC) system. 6M KOH was used as electrolyte at various scan rates of 10, 20, 30 and 50 mVs-1. The results showed that the pore size of carbon increased as the pore size of template increased and the specific capacitance improved as the increasing of the pore size of carbon.

Supported mesoporous carbon ultrafiltration membrane and process for making the same

DOEpatents

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

2004-04-13

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

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

PubMed

Comănescu, Cezar; Capurso, Giovanni; Maddalena, Amedeo

2012-09-28

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

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

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

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

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

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

NASA Astrophysics Data System (ADS)

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

2013-08-01

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

Synthesis, characterization, and performance evaluation of multilayered photoanodes by introducing mesoporous carbon and TiO2 for humic acid adsorption.

PubMed

Hosseini, Soraya; Jahangirian, Hossein; Webster, Thomas J; Soltani, Salman Masoudi; Aroua, Mohamed Kheireddine

2016-01-01

Nanostructured photoanodes were prepared via a novel combination of titanium dioxide (TiO2) nanoparticles and mesoporous carbon (C). Four different photoanodes were synthesized by sol-gel spin coating onto a glassy substrate of fluorine-doped tin oxide. The photocatalytic activities of TiO2, TiO2/C/TiO2, TiO2/C/C/TiO2, and TiO2/C/TiO2/C/TiO2 photoanodes were evaluated by exposing the synthesized photoanodes to UV-visible light. The photocurrent density observed in these photoanodes confirmed that an additional layer of mesoporous carbon could successfully increase the photocurrent density. The highest photocurrent density of ~1.022 mA cm(-2) at 1 V/saturated calomel electrode was achieved with TiO2/C/C/TiO2 under an illumination intensity of 100 mW cm(-2) from a solar simulator. The highest value of surface roughness was measured for a TiO2/C/C/TiO2 combination owing to the presence of two continuous layers of mesoporous carbon. The resulting films had a thickness ranging from 1.605 µm to 5.165 µm after the calcination process. The presence of double-layer mesoporous carbon resulted in a 20% increase in the photocurrent density compared with the TiO2/C/TiO2 combination when only a single mesoporous carbon layer was employed. The improved performance of these photoanodes can be attributed to the enhanced porosity and increased void space due to the presence of mesoporous carbon. For the first time, it has been demonstrated here that the photoelectrochemical performance of TiO2 can be improved by integrating several layers of mesoporous carbon. Comparison of the rate of removal of humic acid by the prepared photoanodes showed that the highest performance from TiO2/C/C/TiO2 was due to the highest photocurrent density generated. Therefore, this study showed that optimizing the sequence of mesoporous carbon layers can be a viable and inexpensive method for enhanced humic acid removal.

Synthesis, characterization, and performance evaluation of multilayered photoanodes by introducing mesoporous carbon and TiO2 for humic acid adsorption

PubMed Central

Hosseini, Soraya; Jahangirian, Hossein; Webster, Thomas J; Soltani, Salman Masoudi; Aroua, Mohamed Kheireddine

2016-01-01

Nanostructured photoanodes were prepared via a novel combination of titanium dioxide (TiO2) nanoparticles and mesoporous carbon (C). Four different photoanodes were synthesized by sol–gel spin coating onto a glassy substrate of fluorine-doped tin oxide. The photocatalytic activities of TiO2, TiO2/C/TiO2, TiO2/C/C/TiO2, and TiO2/C/TiO2/C/TiO2 photoanodes were evaluated by exposing the synthesized photoanodes to UV–visible light. The photocurrent density observed in these photoanodes confirmed that an additional layer of mesoporous carbon could successfully increase the photocurrent density. The highest photocurrent density of ~1.022 mA cm−2 at 1 V/saturated calomel electrode was achieved with TiO2/C/C/TiO2 under an illumination intensity of 100 mW cm−2 from a solar simulator. The highest value of surface roughness was measured for a TiO2/C/C/TiO2 combination owing to the presence of two continuous layers of mesoporous carbon. The resulting films had a thickness ranging from 1.605 µm to 5.165 µm after the calcination process. The presence of double-layer mesoporous carbon resulted in a 20% increase in the photocurrent density compared with the TiO2/C/TiO2 combination when only a single mesoporous carbon layer was employed. The improved performance of these photoanodes can be attributed to the enhanced porosity and increased void space due to the presence of mesoporous carbon. For the first time, it has been demonstrated here that the photoelectrochemical performance of TiO2 can be improved by integrating several layers of mesoporous carbon. Comparison of the rate of removal of humic acid by the prepared photoanodes showed that the highest performance from TiO2/C/C/TiO2 was due to the highest photocurrent density generated. Therefore, this study showed that optimizing the sequence of mesoporous carbon layers can be a viable and inexpensive method for enhanced humic acid removal. PMID:27574426

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

DOE PAGES

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

2014-08-05

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

Structural and morphological properties of mesoporous carbon coated molybdenum oxide films

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

Dayal, Saurabh, E-mail: saurabhdayal153@gmail.com; Kumar, C. Sasi, E-mail: csasimv@gmail.com

2016-05-06

In the present study, we report the structural and morphological properties of mesoporous carbon coated molybdenum oxide films. The deposition of films was carried out in a two-step process, the first step involves deposition of molybdenum and carbon bilayer thin films using DC magnetron sputtering. In the second step the sample was ex-situ annealed in a muffle furnace at different temperatures (400°C to 600°C) and air cooled in the ambient atmosphere. The formation of the meso-porous carbon clusters on molybdenum oxide during the cooling step was investigated using FESEM and AFM techniques. The structural details were explored using XRD. Themore » meso-porous carbon were found growing over molybdenum oxide layer as a result of segregation phenomena.« less

Controllable Synthesis of Ordered Mesoporous Mo2C@Graphitic Carbon Core-Shell Nanowire Arrays for Efficient Electrocatalytic Hydrogen Evolution.

PubMed

Zhu, Jiahui; Yao, Yan; Chen, Zhi; Zhang, Aijian; Zhou, Mengyuan; Guo, Jun; Wu, Winston Duo; Chen, Xiao Dong; Li, Yanguang; Wu, Zhangxiong

2018-06-06

Mo 2 C is a possible substitute to Pt-group metals for electrocatalytic hydrogen evolution reaction (HER). Both support-free and carbon-supported Mo 2 C nanomaterials with improved HER performance have been developed. Herein, distinct from prior research, novel ordered mesoporous core-shell nanowires with Mo 2 C cores and ultrathin graphitic carbon (GC) shells are rationally synthesized and demonstrated to be excellent for HER. The synthesis is fulfilled via a hard-templating approach combining in situ carburization and localized carbon deposition. Phosphomolybdic acid confined in the SBA-15 template is first converted to MoO 2 , which is then in situ carburized to Mo 2 C nanowires with abundant surface defects. Simultaneously, GC layer (the thickness is down to ∼1.0 nm in most areas) is controlled to be locally deposited on the Mo 2 C surface because of its strong affinity with carbon and catalytic effect on graphitization. Removal of the template results in the Mo 2 C@GC core-shell nanowire arrays with the structural properties well-characterized. They exhibit excellent performance for HER with a low overpotential of 125 mV at 10 mA cm -2 , a small Tafel slope of 66 mV dec -1 , and an excellent stability in acidic electrolytes. The influences of several factors, especially the spatial configuration and relative contents of the GC and Mo 2 C components, on HER performance are elucidated with control experiments. The excellent HER performance of the mesoporous Mo 2 C@GC core-shell nanowire arrays originates from the rough Mo 2 C nanowires with diverse active sites and short charge-transfer paths and the ultrathin GC shells with improved surface area, electronic conductivity, and stabilizing effect on Mo 2 C.

Controlling the Pore Size of Mesoporous Carbon Thin Films through Thermal and Solvent Annealing.

PubMed

Zhou, Zhengping; Liu, Guoliang

2017-04-01

Herein an approach to controlling the pore size of mesoporous carbon thin films from metal-free polyacrylonitrile-containing block copolymers is described. A high-molecular-weight poly(acrylonitrile-block-methyl methacrylate) (PAN-b-PMMA) is synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization. The authors systematically investigate the self-assembly behavior of PAN-b-PMMA thin films during thermal and solvent annealing, as well as the pore size of mesoporous carbon thin films after pyrolysis. The as-spin-coated PAN-b-PMMA is microphase-separated into uniformly spaced globular nanostructures, and these globular nanostructures evolve into various morphologies after thermal or solvent annealing. Surprisingly, through thermal annealing and subsequent pyrolysis of PAN-b-PMMA into mesoporous carbon thin films, the pore size and center-to-center spacing increase significantly with thermal annealing temperature, different from most block copolymers. In addition, the choice of solvent in solvent annealing strongly influences the block copolymer nanostructure and the pore size of mesoporous carbon thin films. The discoveries herein provide a simple strategy to control the pore size of mesoporous carbon thin films by tuning thermal or solvent annealing conditions, instead of synthesizing a series of block copolymers of various molecular weights and compositions. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Adsorption of aqueous Cd(II) and Pb(II) on activated carbon nanopores prepared by chemical activation of doum palm shell.

PubMed

Gaya, Umar Ibrahim; Otene, Emmanuel; Abdullah, Abdul Halim

2015-01-01

Non-uniformly sized activated carbons were derived from doum palm shell, a new precursor, by carbonization in air and activation using KOH, NaOH and ZnCl2. The activated carbon fibres were characterised by X-ray diffraction, N2 adsorption-desorption, scanning electron microscopy, particle size analysis and evaluated for Cd(II) and Pb(II) removal. The 40-50 nm size, less graphitic, mesoporous NaOH activated carbon yielded high adsorption efficiency, pointing largely to the influence surface area. The performance of the KOH based activated carbon was arguably explained for the first time in terms of crystallinity. The efficiencies of the mesoporous ZnCl2-formulated activated carbon diminished due to the presence of larger particles. Batch adsorption of divalent metals revealed dependence on adsorbent dose, agitation time, pH and adsorbate concentrations with high adsorption efficiencies at optimum operating parameters. The equilibrium profiles fitted Langmuir and Freundlich isotherms, and kinetics favoured pseudo-second order model. The study demonstrated the practicability of the removal of alarming levels of cadmium and lead ions from industrial effluents.

Mesoporous nitrogen-doped carbon microfibers derived from Mg-biquinoline-dicarboxy compound for efficient oxygen electroreduction

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

Kong, Aiguo, E-mail: agkong@chem.ecnu.edu.cn; Fan, Xiaohong; Chen, Aoling

An in-situ MgO-templating synthesis route was introduced to obtain the mesoporous nitrogen-doped carbon microfibers by thermal conversion of new Mg-2,2′-biquinoline 4,4-dicarboxy acid coordination compound (Mg-DCA) microfibers. The investigated crystal structure of Mg-DCA testified that the assembling of Mg{sup 2+} and DCA through Mg-O coordination bond and hydrogen bond contributed to the formation of one-dimensional (1D) crystalline Mg-DCA microfibers. The nitrogen-doped carbons derived from the pyrolysis of Mg-DCA showed the well-defined microfiber morphology with high mesopore-surface area. Such mesoporous microfibers exhibited the efficient catalytic activity for oxygen reduction reaction (ORR) in alkaline solutions with better stability and methanol-tolerance performance. - Graphicalmore » abstract: Mesoporous nitrogen-doped carbon microfibers with efficient oxygen electroreduction activity were prepared by thermal conversion of new Mg-biquinoline-based coordination compound microfibers.« less

Hydrogenation of succinic acid to 1,4-butanediol over rhenium catalyst supported on copper-containing mesoporous carbon.

PubMed

Hong, Ung Gi; Park, Hai Woong; Lee, Joongwon; Hwang, Sunhwan; Kwak, Jimin; Yi, Jongheop; Song, In Kyu

2013-11-01

Copper-containing mesoporous carbon (Cu-MC) was prepared by a single-step surfactant-templating method. For comparison, copper-impregnated mesoporous carbon (Cu/MC) was also prepared by a surfactant-templating method and a subsequent impregnation method. Rhenium catalysts supported on copper-containing mesoporous carbon and copper-impregnated mesoporous carbon (Re/Cu-MC and Re/Cu/MC, respectively) were then prepared by an incipient wetness method, and they were applied to the liquid-phase hydrogenation of succinic acid to 1,4-butanediol (BDO). It was observed that copper in the Re/Cu-MC catalyst was well incorporated into carbon framework, resulting in higher surface area and larger pore volume than those of Re/Cu/MC catalyst. Therefore, Re/Cu-MC catalyst showed higher copper dispersion than Re/Cu/MC catalyst, although both catalysts retained the same amounts of copper and rhenium. In the liquid-phase hydrogenation of succinic acid to BDO, Re/Cu-MC catalyst showed a better catalytic activity than Re/Cu/MC catalyst. Fine dispersion of copper in the Re/Cu-MC catalyst was responsible for its enhanced catalytic activity.

Kinetic and calorimetric study of the adsorption of dyes on mesoporous activated carbon prepared from coconut coir dust.

PubMed

Macedo, Jeremias de Souza; da Costa Júnior, Nivan Bezerra; Almeida, Luis Eduardo; Vieira, Eunice Fragoso da Silva; Cestari, Antonio Reinaldo; Gimenez, Iara de Fátima; Villarreal Carreño, Neftali Lênin; Barreto, Ledjane Silva

2006-06-15

Mesoporous activated carbon has been prepared from coconut coir dust as support for adsorption of some model dye molecules from aqueous solutions. The methylene blue (MB) and remazol yellow (RY) molecules were chosen for study of the adsorption capacity of cationic and anionic dyes onto prepared activated carbon. The adsorption kinetics was studied with the Lagergren first- and pseudo-second-order kinetic models as well as the intraparticle diffusion model. The results for both dyes suggested a multimechanism sorption process. The adsorption mechanisms in the systems dyes/AC follow pseudo-second-order kinetics with a significant contribution of intraparticle diffusion. The samples simultaneously present acidic and basic sites able to act as anchoring sites for basic and acidic dyes, respectively. Calorimetric studies reveal that dyes/AC interaction forces are correlated with the pH of the solution, which can be related to the charge distribution on the AC surface. These AC samples also exhibited very short equilibrium times for the adsorption of both dyes, which is an economically favorable requisite for the activated carbon described in this work, in addition to the local abundance of the raw material.

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

NASA Astrophysics Data System (ADS)

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

2014-01-01

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

Nitrogen-Doped Ordered Mesoporous Carbon Supported Bimetallic PtCo Nanoparticles for Upgrading of Biophenolics.

PubMed

Wang, Guang-Hui; Cao, Zhengwen; Gu, Dong; Pfänder, Norbert; Swertz, Ann-Christin; Spliethoff, Bernd; Bongard, Hans-Josef; Weidenthaler, Claudia; Schmidt, Wolfgang; Rinaldi, Roberto; Schüth, Ferdi

2016-07-25

Hydrodeoxygenation (HDO) is an attractive route for the upgrading of bio-oils produced from lignocellulose. Current catalysts require harsh conditions to effect HDO, decreasing the process efficiency in terms of energy and carbon balance. Herein we report a novel and facile method for synthesizing bimetallic PtCo nanoparticle catalysts (ca. 1.5 nm) highly dispersed in the framework of nitrogen-doped ordered mesoporous carbon (NOMC) for this reaction. We demonstrate that NOMC with either 2D hexagonal (p6m) or 3D cubic (Im3‾ m) structure can be easily synthesized by simply adjusting the polymerization temperature. We also demonstrate that PtCo/NOMC (metal loading: Pt 9.90 wt %; Co 3.31 wt %) is a highly effective catalyst for HDO of phenolic compounds and "real-world" biomass-derived phenolic streams. In the presence of PtCo/NOMC, full deoxygenation of phenolic compounds and a biomass-derived phenolic stream is achieved under conditions of low severity. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Sustainable development of tyre char-based activated carbons with different textural properties for value-added applications.

PubMed

Hadi, Pejman; Yeung, Kit Ying; Guo, Jiaxin; Wang, Huaimin; McKay, Gordon

2016-04-01

This paper aims at the sustainable development of activated carbons for value-added applications from the waste tyre pyrolysis product, tyre char, in order to make pyrolysis economically favorable. Two activation process parameters, activation temperature (900, 925, 950 and 975 °C) and residence time (2, 4 and 6 h) with steam as the activating agent have been investigated. The textural properties of the produced tyre char activated carbons have been characterized by nitrogen adsorption-desorption experiments at -196 °C. The activation process has resulted in the production of mesoporous activated carbons confirmed by the existence of hysteresis loops in the N2 adsorption-desorption curves and the pore size distribution curves obtained from BJH method. The BET surface area, total pore volume and mesopore volume of the activated carbons from tyre char have been improved to 732 m(2)/g, 0.91 cm(3)/g and 0.89 cm(3)/g, respectively. It has been observed that the BET surface area, mesopore volume and total pore volume increased linearly with burnoff during activation in the range of experimental parameters studied. Thus, yield-normalized surface area, defined as the surface area of the activated carbon per gram of the precursor, has been introduced to optimize the activation conditions. Accordingly, the optimized activation conditions have been demonstrated as an activation temperature of 975 °C and an activation time of 4 h. Copyright © 2016 Elsevier Ltd. All rights reserved.

Breakthrough and future: nanoscale controls of compositions, morphologies, and mesochannel orientations toward advanced mesoporous materials.

PubMed

Yamauchi, Yusuke; Suzuki, Norihiro; Radhakrishnan, Logudurai; Wang, Liang

2009-01-01

Currently, ordered mesoporous materials prepared through the self-assembly of surfactants have attracted growing interests owing to their special properties, including uniform mesopores and a high specific surface area. Here we focus on fine controls of compositions, morphologies, mesochannel orientations which are important factors for design of mesoporous materials with new functionalities. This Review describes our recent progress toward advanced mesoporous materials. Mesoporous materials now include a variety of inorganic-based materials, for example, transition-metal oxides, carbons, inorganic-organic hybrid materials, polymers, and even metals. Mesoporous metals with metallic frameworks can be produced by using surfactant-based synthesis with electrochemical methods. Owing to their metallic frameworks, mesoporous metals with high electroconductivity and high surface areas hold promise for a wide range of potential applications, such as electronic devices, magnetic recording media, and metal catalysts. Fabrication of mesoporous materials with controllable morphologies is also one of the main subjects in this rapidly developing research field. Mesoporous materials in the form of films, spheres, fibers, and tubes have been obtained by various synthetic processes such as evaporation-mediated direct templating (EDIT), spray-dried techniques, and collaboration with hard-templates such as porous anodic alumina and polymer membranes. Furthermore, we have developed several approaches for orientation controls of 1D mesochannels. The macroscopic-scale controls of mesochannels are important for innovative applications such as molecular-scale devices and electrodes with enhanced diffusions of guest species. Copyright 2009 The Japan Chemical Journal Forum and Wiley Periodicals, Inc.

Dimethyl Methylphosphonate Adsorption Capacities and Desorption Energies on Ordered Mesoporous Carbons.

PubMed

Huynh, Kim; Holdren, Scott; Hu, Junkai; Wang, Luning; Zachariah, Michael R; Eichhorn, Bryan W

2017-11-22

In this study, we determine effective adsorption capacities and desorption energies for DMMP with highly ordered mesoporous carbons (OMCs), 1D cylindrical FDU-15, 3D hexagonal CMK-3, 3D bicontinuous CMK-8, and as a reference, microporous BPL carbon. After exposure to DMMP vapor at room temperature for approximately 70 and 800 h, the adsorption capacity of DMMP for each OMC was generally proportional to the total surface area and pore volume, respectively. Desorption energies of DMMP were determined using a model-free isoconversional method applied to thermogravimetric analysis (TGA) data. Our experiments determined that DMMP saturated carbon will desorb any weakly bound DMMP from pores >2.4 nm at room temperature, and no DMMP will adsorb into pores smaller than 0.5 nm. The calculated desorption energies for high surface coverages, 25% DMMP desorbed from pores ≤2.4 nm, are 68-74 kJ mol -1 , which is similar to the DMMP heat of vaporization (52 kJ mol -1 ). At lower surface coverages, 80% DMMP desorbed, the DMMP desorption energies from the OMCs are 95-103 kJ mol -1 . This is overall 20-30 kJ mol -1 higher in comparison to that of BPL carbon, due to the pore size and diffusion through different porous networks.

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

PubMed

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

2010-03-15

To detect organophosphate chemicals, which are used both as pesticides and as nerve agents, a novel biosensor based on organophosphorus hydrolase was developed. By using mesoporous carbon (MC) and carbon black (CB) as an anodic layer, the sensitivity of the sensor to p-nitrophenol (PNP), which is the product of the organophosphorus hydrolase reaction, was greatly improved. The MC/CB/glass carbon (GC) layer exhibited an enhanced amperometric response relative to a carbon nanotube (CNT)-modified electrode because it promoted electron transfer of enzymatically generated phenolic compounds (p-nitrophenol). The well-ordered nanopores, many edge-plane-like defective sites (EDSs), and high surface area of the MC resulted in increased sensitivity, and allowed for nanomolar-range detection of the analyte paraoxon. Thus, MCs are suitable for use in real-time biosensors. Under the optimized experimental conditions, the biosensor had a detection limit of 0.12 microM (36 ppb) and a sensitivity of 198 nA/microM for paraoxon. (c) 2009 Elsevier B.V. All rights reserved.

Adsorption of CO₂, CH₄, and N₂ on ordered mesoporous carbon: approach for greenhouse gases capture and biogas upgrading.

PubMed

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

2013-05-21

Separation of CO₂ and N₂ from CH₄ is significantly important in natural gas upgrading, and capture/removal of CO₂, CH₄ from air (N₂) is essential to greenhouse gas emission control. Adsorption equilibrium and kinetics of CO₂, CH₄, and N₂ on an ordered mesoporous carbon (OMC) sample were systematically investigated to evaluate its capability in the above two applications. The OMC was synthesized and characterized with TEM, TGA, small-angle XRD, and nitrogen adsorption/desorption measurements. Pure component adsorption isotherms of CO₂, CH₄, and N₂ were measured at 278, 298, and 318 K and pressures up to 100 kPa, and correlated with the Langmuir model. These data were used to estimate the separation selectivities for CO₂/CH₄, CH₄/N₂, and CO₂/N₂ binary mixtures at different compositions and pressures according to the ideal adsorbed solution theory (IAST) model. At 278 K and 100 kPa, the predicted selectivities for equimolar CO₂/CH₄, CH4/N₂, and CO₂/N₂ are 3.4, 3.7, and 12.8, respectively; and the adsorption capacities for CH₄ and CO₂ are 1.3 and 3.0 mmol/g, respectively. This is the first report of a versatile mesoporous material that displays both high selectivities and large adsorption capacities for separating CO₂/CH₄, CH₄/N₂, and CO₂/N₂ mixtures.

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

PubMed

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

2012-09-01

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

Effect of pre-pyrolysis mode on simultaneous introduction of nitrogen/oxygen-containing functional groups into the structure of bagasse-based mesoporous carbon and its influence on Cu(II) adsorption.

PubMed

Wan, Zeqing; Li, Kunquan

2018-03-01

A convenient effective microwave pre-pyrolysis treatment to synthesize biomass-based mesoporous carbon with higher nitrogen/oxygen-chelating adsorption for Cu(II) is reported here, in which phosphoric acid impregnated bagasse was used as a microwave absorber and porogen. For comparison, conventional electric-heating pyrolyzed carbon was prepared and doped with nitrogen/oxygen groups. Nitrogen adsorption, scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy (XPS) and batch adsorption were employed to investigate the effects of the two pre-pyrolysis modes on the sample physicochemical and Cu(II) adsorptive properties. The 22-min-microwave-pyrolyzed bagasse mesoporous activated carbon (MBAC, 85.32% mesoporosity) contained 10.52% O, which is 3.94% more than electric-heating pyrolyzed mesoporous activated carbon (89.52% mesoporosity). After electrophilic aromatic substitutions of N/O doping, the former possessed more N (5.83%) and more O (21.40%), confirming that time-saving energy-efficient microwave pyrolysis favors the formation of defective C/O atoms in or at the edges of the graphite layer of MBAC, which are highly active and tend to act as preferred reactive positions for the doping of N/O-containing groups simultaneously compared with conventional electric-heating pyrolysis. These N and O species existed mainly as COOH, OH, NH and NH 2 functional groups, and were confirmed by XPS to be active sites for metal binding via electrostatic attraction, hydrogen bonding, a chelate effect and complexation, resulting in the great enhancement of Cu(II) adsorption. Langmuir isotherm and pseudo-second-order kinetic fitting further proved that Cu(II) adsorption by N/O-doped MBAC is ascribed mainly to chemisorption. Therefore, rapid microwave pre-pyrolysis provides a promising route to prepare excellent-performance N/O-doped carbon adsorbents. Copyright © 2017 Elsevier Ltd. All rights reserved.

Nitrogen-doped MOF-derived micropores carbon as immobilizer for small sulfur molecules as a cathode for lithium sulfur batteries with excellent electrochemical performance.

PubMed

Li, Zhaoqiang; Yin, Longwei

2015-02-25

Nitrogen-doped carbon (NDC) spheres with abundant 22 nm mesopores and 0.5 nm micropores are obtained by directly carbonization of nitrogen-contained metal organic framework (MOF) nanocrystals. Large S8 and small S2-4 molecules are successfully infiltrated into 22 nm mesopores and 0.5 nm micropores, respectively. We successfully investigate the effect of sulfur immobilization in mesopores and micropores on the electrochemical performance of lithium-sulfur (Li-S) battery based on NDC-sulfur hybrid cathodes. The large S8 molecules in 22 nm mesopores can be removed by a prolonged heat treatment, with only small molecules of S2-4 immobilized in micropores of NDC matrices. The NDC/S2-4 hybrid exhibits excellent cycling performance, high Coulombic efficiency, and good rate capability as cathode for Li-S batteries. The confinement of smaller S2-4 molecules in the micropores of NDS efficiently avoids the loss of active sulfur and formation of soluble high-order Li polysulfides. The porous carbon can buffer the volume expansion and contraction changes, promising a stable structure for cathode. Furthermore, N doping in MOF-derived carbon not only facilitates the fast charge transfer but also is helpful in building a stronger interaction between carbon and sulfur, strengthening immobilization ability of S2-4 in micropores. The NDS-sulfur hybrid cathode exhibits a reversible capacity of 936.5 mAh g(-1) at 100th cycle with a Coulombic efficiency of 100% under a current density of 335 mA g(-1). It displays a superior rate capability performance, delivering a capacity of 632 mAh g(-1) at a high rate of 5 A g(-1). This uniquely porous NDC derived from MOF nanocrystals could be applied in related high-energy storage devices.

Mesoporous activated carbon prepared from NaOH activation of rattan (Lacosperma secundiflorum) hydrochar for methylene blue removal.

PubMed

Islam, Md Azharul; Ahmed, M J; Khanday, W A; Asif, M; Hameed, B H

2017-04-01

Hydrothermal carbonization of biomass wastes presents a promising step in the production of cost-effective activated carbon. In the present work, mesoporous activated carbon (HAC) was prepared by the hydrothermal carbonization of rattan furniture wastes followed by NaOH activation. The textural and morphological characteristics, along with adsorption performance of prepared HAC toward methylene blue (MB) dye, were evaluated. The effects of common adsorption variables on performance resulted in a removal efficiency of 96% for the MB sample at initial concentration of 25mg/L, solution pH of 7, 30°C, and 8h. The Langmuir equation showed the best isotherm data correlation, with a maximum uptake of 359mg/g. The adsorbed amount versus time data was well fitted by a pseudo-second order kinetic model. The prepared HAC with a high surface area of 1135m 2 /g and an average pore size distribution of 35.5Å could be an efficient adsorbent for treatment of synthetic dyes in wastewaters. Copyright © 2017 Elsevier Inc. All rights reserved.

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

NASA Astrophysics Data System (ADS)

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

2013-05-01

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

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

PubMed

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

2013-06-07

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

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

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

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

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

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

PubMed

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

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 120 min, and the equilibrated adsorption capacity increased from 99.38 to 310.78 mg/g with the increase of initial concentration of 2,4-D from 100 to 500 mg/L. Notablely, the adsorption capacity reached 97% of the maximum within the first 5 min. 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. Copyright © 2014 Elsevier Inc. All rights reserved.

Ordered Mesoporous Titania/Carbon Hybrid Monoliths for Lithium-ion Battery Anodes with High Areal and Volumetric Capacity.

PubMed

Dörr, Tobias S; Fleischmann, Simon; Zeiger, Marco; Grobelsek, Ingrid; de Oliveira, Peter W; Presser, Volker

2018-04-25

Free-standing, binder-free, and conductive additive-free mesoporous titanium dioxide/carbon hybrid electrodes were prepared from co-assembly of a poly(isoprene)-block-poly(styrene)-block-poly(ethylene oxide) block copolymer and a titanium alkoxide. By tailoring an optimized morphology, we prepared macroscopic mechanically stable 300 μm thick monoliths that were directly employed as lithium-ion battery electrodes. High areal mass loading of up to 26.4 mg cm -2 and a high bulk density of 0.88 g cm -3 were obtained. This resulted in a highly increased volumetric capacity of 155 mAh cm -3 , compared to cast thin film electrodes. Further, the areal capacity of 4.5 mAh cm -2 represented a 9-fold increase compared to conventionally cast electrodes. These attractive performance metrics are related to the superior electrolyte transport and shortened diffusion lengths provided by the interconnected mesoporous nature of the monolith material, assuring superior rate handling, even at high cycling rates. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

PubMed

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

2017-12-27

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

Magnetic N-doped mesoporous carbon as an adsorbent for the magnetic solid-phase extraction of phthalate esters from soft drinks.

PubMed

Li, Menghua; Jiao, Caina; Yang, Xiumin; Wang, Chun; Wu, Qiuhua; Wang, Zhi

2017-04-01

A new kind of magnetic N-doped mesoporous carbon was prepared by the one-step carbonization of a hybrid precursor (glucose, melamine, and iron chloride) in a N 2 atmosphere with a eutectic salt (KCl/ZnCl 2 ) as the porogen. The obtained magnetic N-doped mesoporous carbon showed excellent characteristics, such as strong magnetic response, high surface area, large pore volume, and abundant π-electron system, which endow it with a great potential as a magnetic solid-phase extraction adsorbent. To evaluate its adsorption performance, the magnetic N-doped mesoporous carbon was used for the extraction of three phthalate esters from soft drink samples followed by high-performance liquid chromatographic analysis. Under the optimum conditions, the developed method showed a good linearity (1.0-120.0 ng/mL), low limit of detection (0.1-0.3 ng/mL, S/N = 3), and good recoveries (83.2-119.0%) in soft drink samples. The results indicated that the magnetic N-doped mesoporous carbon has an excellent adsorption capacity for phthalate esters and the present method is simple, accurate, and highly efficient for the extraction and determination of phthalate esters in complex matrix samples. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Flexible and weaveable capacitor wire based on a carbon nanocomposite fiber.

PubMed

Ren, Jing; Bai, Wenyu; Guan, Guozhen; Zhang, Ye; Peng, Huisheng

2013-11-06

A flexible and weaveable electric double-layer capacitor wire is developed by twisting two aligned carbon nanotube/ordered mesoporous carbon composite fibers with remarkable mechanical and electronic properties as electrodes. This capacitor wire exhibits high specific capacitance and long life stability. Compared with the conventional planar structure, the capacitor wire is also lightweight and can be integrated into various textile structures that are particularly promising for portable and wearable electronic devices. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The development of chiral nematic mesoporous materials.

PubMed

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

2014-04-15

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

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

PubMed

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

2013-11-01

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

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

NASA Astrophysics Data System (ADS)

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

2016-06-01

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

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

NASA Astrophysics Data System (ADS)

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

2015-06-01

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

MoO2-ordered mesoporous carbon hybrids as anode materials with highly improved rate capability and reversible capacity for lithium-ion battery.

PubMed

Chen, Ailian; Li, Caixia; Tang, Rui; Yin, Longwei; Qi, Yongxin

2013-08-28

A novel hybrid of MoO2-ordered mesoporous carbon (MoO2-OMC) was prepared through a two-step solvothermal chemical reaction route. The electrochemical performances of the mesoporous MoO2-OMC hybrids were examined using galvanostatical charge-discharge, cyclic voltammetry, and electrochemical impedance spectroscopy (EIS) techniques. The MoO2-OMC hybrid exhibits significantly improved electrochemical performance of high reversible capacity, high-rate capability, and excellent cycling performance as an anode electrode material for Li ion batteries. It is revealed that the MoO2-OMC hybrid could deliver the first discharge capacity of 1641.8 mA h g(-1) with an initial Coulombic efficiency of 63.6%, and a reversible capacity as high as 1049.1 mA h g(-1) even after 50 cycles at a current density of 100 mA g(-1), much higher than the theoretical capacity of MoO2 (838 mA h g(-1)) and OMC materials. The MoO2-OMC hybrid demonstrates an excellent high rate capability with capacity of ∼600 mA h g(-1) even at a charge current density of 1600 mA g(-1) after 50 cycles, which is approximately 11.1 times higher than that of the OMC (54 mA h g(-1)) materials. The improved rate capability and reversible capacity of the MoO2-OMC hybrid are attributed to a synergistic reaction between the MoO2 nanoparticles and mesoporous OMC matrices. It is noted that the electrochemical performance of the MoO2-OMC hybrid is evidently much better than the previous MoO2-based hybrids.

Origin of melting point depression for rare gas solids confined in carbon pores

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

Morishige, Kunimitsu, E-mail: morishi@chem.ous.ac.jp; Kataoka, Takaaki

To obtain insights into the mechanism of the melting-point depression of rare gas solids confined in crystalline carbon pores, we examined the freezing and melting behavior of Xe and Ar confined to the crystalline pores of ordered mesoporous carbons as well as compressed exfoliated graphite compared to the amorphous pores of ordered mesoporous silicas, by means of X-ray diffraction. For the Xe and Ar confined to the crystalline carbon pores, there was no appreciable thermal hysteresis between freezing and melting. Furthermore, the position of the main diffraction peak did not change appreciably on freezing and melting. This strongly suggests thatmore » the liquids confined in the carbon pores form a multilayered structure parallel to the smooth walls. For the Xe and Ar confined to the amorphous silica pores, on the other hand, the position of the main diffraction peak shifted into higher scattering angle on freezing suggested that the density of the confined solid is distinctly larger than for the confined liquid. Using compressed exfoliated graphite with carbon walls of higher crystallinity, we observed that three-dimensional (3D) microcrystals of Xe confined in the slit-shaped pores melted to leave the unmelted bilayers on the pore walls below the bulk triple point. The lattice spacing of the 3D microcrystals confined is larger by ∼0.7% than that of the bilayer next to the pore walls in the vicinity of the melting point.« less

Sandwich-like graphene-mesoporous carbon as sulfur host for enhanced lithium-sulfur batteries

NASA Astrophysics Data System (ADS)

Tian, Ting; Li, Bin; Zhu, Mengqi; Liu, Jianhua; Li, Songmei

2017-10-01

Graphene-mesoporous carbon/sulfur composites (G-MPC/S) were constructed by melt-infiltration of sulfur into graphene-mesoporous carbon which was synthesized by soft template method. The SEM and BET results of the graphene-mesoporous carbon show that the as-prepared sandwich-like G-MPC composites with a unique microporous-mesoporous structure had a high specific surface area of 554.164 m2 · g-1 and an average pore size of about 13 nm. The XRD analysis presents the existence of orthorhombic sulfur in the G-MPC/S composite, which indicates the complete infiltration of sulfur into the pores of the G-MPC. When the graphene-mesoporous carbon/surfur composites (G-MPC/S) with 53.9 wt.% sulfur loading were used as the cathode for lithium-sulfur (Li-S) batteries, it exhibited an outstanding electrochemical performance including excellent initial discharge specific capacity of 1393 mAh · g-1 at 0.1 °C, high cycle stability (731 mAh · g-1 at 200 cycles) and good rate performance (1038 mAh · g-1, 770 mAh · g-1, 518 mAh · g-1 and 377 mAh · g-1 at 0.1 °C, 0.2 °C, 0.5 °C and 1 °C, respectively), which suggested the important role of the G-MPC composite in providing more electrons and ions channels, in addition, the shuttle effect caused by the dissolved polysulfide was also suppressed.

Oxidized template-synthesized mesoporous carbon with pH-dependent adsorption activity: A promising adsorbent for removal of hydrophilic ionic liquid

NASA Astrophysics Data System (ADS)

Zhang, Ling; Cao, Wugang; Alvarez, Pedro J. J.; Qu, Xiaolei; Fu, Heyun; Zheng, Shourong; Xu, Zhaoyi; Zhu, Dongqiang

2018-05-01

Aiming to remove ionic liquid pollutants from water, an ordered mesoporous carbon CMK-3 (OMC) was prepared and modified by oxidation with nitric acid. A commercial microporous activated carbon adsorbent, Filtrasorb-300 (AC), was used as benchmark. Boehm titration showed that oxidized OMC had a substantially higher oxygen content than oxidized AC. Adsorption of the hydrophilic imidazolium-based ionic liquid 1-Butyl-3-methylimidazolium chloride ([Bmim]Cl) on OMC and AC was well-described by the Freundlich isotherm model. Surface oxidation markedly enhanced [Bmim]Cl adsorption by both OMC and AC. Nevertheless, [Bmim]Cl adsorption was much higher on oxidized OMC than on oxidized AC. Increasing pH had negligible influence on [Bmim]Cl adsorption on pristine OMC, but enhanced adsorption on oxidized OMC. Regeneration tests showed stable performance of oxidized OMC over five adsorption-desorption cycles. Thus, oxidized OMC can be a highly effective adsorbent for the removal of hydrophilic ionic liquids from water.

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

Gencoglu, Maria F.; Spurri, Amanda; Franko, Mitchell

We report that soft-templated mesoporous carbon is morphologically a non-nano type of carbon. It is a relatively newer variety of biomaterial, which has already demonstrated its successful role in drug delivery applications. To investigate the toxicity and biocompatibility, we introduced three types of mesoporous carbons with varying synthesis conditions and pore textural properties. We compared the Brunauer–Emmett–Teller (BET) surface area and pore width and performed cytotoxicity experiments with HeLa cells, cell viability studies with fibroblast cells and hemocomapatibility studies. Cytotoxicity tests reveal that two of the carbons are not cytotoxic, with cell survival over 90%. The mesoporous carbon with themore » highest surface area showed slight toxicity (~70% cell survival) at the highest carbon concentration of 500 μg/mL. Fibroblast cell viability assays suggested high and constant viability of over 98% after 3 days with no apparent relation with materials property and good visible cell-carbon compatibility. No hemolysis (<1%) was confirmed for all the carbon materials. Protein adsorption experiments with bovine serum albumin (BSA) and fibrinogen revealed a lower protein binding capacity of 0.2–0.6 mg/m 2 and 2–4 mg/m 2 for BSA and fibrinogen, respectively, with lower binding associated with an increase in surface area. The results of this study confirm the biocompatibility of soft-templated mesoporous carbons.« less

Solvent-Free Self-Assembly to the Synthesis of Nitrogen-Doped Ordered Mesoporous Polymers for Highly Selective Capture and Conversion of CO2.

PubMed

Liu, Fujian; Huang, Kuan; Wu, Qin; Dai, Sheng

2017-07-01

A solvent-free induced self-assembly technology for the synthesis of nitrogen-doped ordered mesoporous polymers (N-OMPs) is developed, which is realized by mixing polymer precursors with block copolymer templates, curing at 140-180 °C, and calcination to remove the templates. This synthetic strategy represents a significant advancement in the preparation of functional porous polymers through a fast and scalable yet environmentally friendly route, since no solvents or catalysts are used. The synthesized N-OMPs and their derived catalysts are found to exhibit competitive CO 2 capacities (0.67-0.91 mmol g -1 at 25 °C and 0.15 bar), extraordinary CO 2 /N 2 selectivities (98-205 at 25 °C), and excellent activities for catalyzing conversion of CO 2 into cyclic carbonate (conversion >95% at 100 °C and 1.2 MPa for 1.5 h). The solvent-free technology developed in this work can also be extended to the synthesis of N-OMP/SiO 2 nanocomposites, mesoporous SiO 2 , crystalline mesoporous TiO 2 , and TiPO, demonstrating its wide applicability in porous material synthesis. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

PubMed

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

2013-03-15

Adsorptive separations of C(2)H(6)/CH(4) and CH(4)/N(2) binary mixtures are of paramount importance from the energy and environmental points of view. A mesoporous carbon adsorbent was synthesized using a soft template method and characterized with TEM, TGA, and nitrogen adsorption/desorption. Adsorption equilibrium and kinetics of C(2)H(6), CH(4), and N(2) on the mesoporous carbon adsorbent were determined at 278, 298, and 318 K and pressures up to 100 kPa. The adsorption capacities of C(2)H(6) and CH(4) on the mesoporous carbon adsorbent at 298 K and 100 kPa are 2.20 mmol/g and 1.05 mmol/g, respectively. Both are significantly higher than those of many adsorbents including pillared clays and ETS-10 at a similar condition. The equilibrium selectivities of C(2)H(6)/CH(4) and CH(4)/N(2) at 298 K are 19.6 and 5.8, respectively. It was observed that the adsorption of C(2)H(6), CH(4), and N(2) gases on the carbon adsorbent was reversible with modest isosteric heats of adsorption, which implies that this carbon adsorbent can be easily regenerated in a cyclic adsorption process. These results suggest that the mesoporous carbon studied in this work is a promising alternative adsorbent for the separations of C(2)H(6)/CH(4) and CH(4)/N(2) gas mixtures. Copyright © 2012 Elsevier Inc. All rights reserved.

Hierarchically ordered mesoporous carbon/graphene composites as supercapacitor electrode materials.

PubMed

Song, Yanjie; Li, Zhu; Guo, Kunkun; Shao, Ting

2016-08-25

Hierarchically ordered mesoporous carbon/graphene (OMC/G) composites have been fabricated by means of a solvent-evaporation-induced self-assembly (EISA) method. The structures of these composites are characterized by X-ray diffraction, transmission electron microscopy, Raman spectroscopy and nitrogen adsorption-desorption at 77 K. These results indicate that OMC/G composites possess the hierarchically ordered hexagonal p6mm mesostructure with the lattice unit parameter and pore diameter close to 10 nm and 3 nm, respectively. The specific surface area of OMC/G composites after KOH activation is high up to 2109.2 m(2) g(-1), which is significantly greater than OMC after activation (1474.6 m(2) g(-1)). Subsequently, the resulting OMC/G composites as supercapacitor electrode materials exhibit an outstanding capacitance as high as 329.5 F g(-1) in 6 M KOH electrolyte at a current density of 0.5 A g(-1), which is much higher than both OMC (234.2 F g(-1)) and a sample made by mechanical mixing of OMC with graphene (217.7 F g(-1)). In addition, the obtained OMC/G composites display good cyclic stability, and the final capacitance retention is approximately 96% after 5000 cycles. These ordered mesopores in the OMC/G composites are beneficial to the accessibility and rapid diffusion of the electrolyte, while graphene in OMC/G composites can also facilitate the transport of electrons during the processes of charging and discharging owing to its high conductivity, thereby leading to an excellent energy storage performance. The method demonstrated in this work would open up a new route to design and develop graphene-based architectures for supercapacitor applications.

Micro-/mesoporous carbons for controlled release of antipyrine and indomethacin

DOE PAGES

Saha, Dipendu; Moken, Tara; Chen, Jihua; ...

2015-02-24

Here, we have demonstrated the potential of meso- and microporous carbons in controlled release applications and targeted oral drug delivery. We have employed two mesoporous and two microporous carbons for the sustained release of one water-soluble drug (antipyrine) and one water-insoluble drug (indomethacin), using these as models to examine the controlled release characteristics. The micro-/mesoporous carbons were characterized as having a BET surface area of 372–2251 m 2 g –1 and pore volume 0.63–1.03 cm 3 g –1. The toxicity studies with E. coli bacterial cells did not reveal significant toxicity, which is in accordance with our previous studies onmore » human cells with similar materials. Mucin adsorption tests with type III pork mucin demonstrated 20–30% mucin adsorption by the carbon samples and higher mucin adsorption could be attributed to higher surface area and more oxygen functionalities. Antipyrine and indomethacin loading was 6–78% in these micro-/mesoporous carbons. The signatures in thermogravimetric studies revealed the presence of drug molecules within the porous moieties of the carbon. The partial shifting of the decomposition peak of the drug adsorbed within the carbon pores was caused by the confinement of drug molecules within the narrow pore space of the carbon. The release profiles of both drugs were examined in simulated gastric fluid (pH = 1.2) and in three other release media with respective pH values of 4.5, 6.8 and 7.4, along with varying residence times to simulate the physiological conditions of the stomach, duodenum, small intestine and colon, respectively. All the release profiles manifested diffusion controlled sustained release that corroborates the effective role of micro-/mesoporous carbons as potential drug carriers.« less

Micro-/mesoporous carbons for controlled release of antipyrine and indomethacin

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

Saha, Dipendu; Moken, Tara; Chen, Jihua

Here, we have demonstrated the potential of meso- and microporous carbons in controlled release applications and targeted oral drug delivery. We have employed two mesoporous and two microporous carbons for the sustained release of one water-soluble drug (antipyrine) and one water-insoluble drug (indomethacin), using these as models to examine the controlled release characteristics. The micro-/mesoporous carbons were characterized as having a BET surface area of 372–2251 m 2 g –1 and pore volume 0.63–1.03 cm 3 g –1. The toxicity studies with E. coli bacterial cells did not reveal significant toxicity, which is in accordance with our previous studies onmore » human cells with similar materials. Mucin adsorption tests with type III pork mucin demonstrated 20–30% mucin adsorption by the carbon samples and higher mucin adsorption could be attributed to higher surface area and more oxygen functionalities. Antipyrine and indomethacin loading was 6–78% in these micro-/mesoporous carbons. The signatures in thermogravimetric studies revealed the presence of drug molecules within the porous moieties of the carbon. The partial shifting of the decomposition peak of the drug adsorbed within the carbon pores was caused by the confinement of drug molecules within the narrow pore space of the carbon. The release profiles of both drugs were examined in simulated gastric fluid (pH = 1.2) and in three other release media with respective pH values of 4.5, 6.8 and 7.4, along with varying residence times to simulate the physiological conditions of the stomach, duodenum, small intestine and colon, respectively. All the release profiles manifested diffusion controlled sustained release that corroborates the effective role of micro-/mesoporous carbons as potential drug carriers.« less

Micro-mesoporous carbon spheres derived from carrageenan as electrode material for supercapacitors

NASA Astrophysics Data System (ADS)

Fan, Yang; Yang, Xin; Zhu, Bing; Liu, Pei-Fang; Lu, Hai-Ting

2014-12-01

The polysaccharide carrageenan is used as a natural precursor to prepare micro-mesoporous carbon spheres. The carbon spheres were synthesized by hydrothermal carbonization of carrageenan, and subsequent chemical activation by KOH at different temperatures. The obtained micro-mesoporous carbon spheres have high surface area (up to 2502 m2 g-1) and large pore volume (up to 1.43 cm3 g-1). Moreover, the micro- and mesoporosity can be finely tuned be modifying the activation temperatures in the range of 700-900 °C. The carbon spheres activated at 900 °C present high specific capacitance of 230 F g-1 at a current density of 1 A g-1 and good ion transport kinetics. The good capacitive performance can be ascribed to the high specific surface area, well-controlled micro- and mesoporosity and narrow pore size distribution.

Carbon and Mo transformations during the synthesis of mesoporous Mo2C/carbon catalysts by carbothermal hydrogen reduction

NASA Astrophysics Data System (ADS)

Wang, Haiyan; Liu, Shida; Liu, Bing; Montes, Vicente; Hill, Josephine M.; Smith, Kevin J.

2018-02-01

The synthesis of mesoporous Mo2C/carbon catalysts by carbothermal hydrogen reduction is reported. Petroleum coke (petcoke) was activated with KOH at 800 °C to obtain high surface area microporous activated petcoke (APC; 2000 m2/g). The APC was wet impregnated with ammonium heptamolybdate (AHM: 10 wt% Mo), dried and reduced in H2 at temperatures from 400 to 800 °C, to yield Mo2C/APC catalysts. Increased reduction temperature increased the Mo2C yield and the mesoporous volume of the Mo2C/APC. At a reduction temperature of 750 °C the mesopore volume of the catalyst doubled compared to the APC support and accounted for 37% of the total pore volume. Maintaining the final CHR temperature for 90 min further increased the Mo2C yield and mesoporosity of the catalyst. The role of Mo2C in the catalytic hydrogenation of the APC and mesopore generation is demonstrated. The activity of the Mo2C/carbon catalysts in the hydrodeoxygenation of 4-methyl phenol increased with increased CHR temperature and catalyst mesoporosity.

Enhanced photo-catalytic activity of ordered mesoporous indium oxide nanocrystals in the conversion of CO2 into methanol.

PubMed

Gondal, M A; Dastageer, M A; Oloore, L E; Baig, U; Rashid, S G

2017-07-03

Ordered mesoporous indium oxide nanocrystal (m-In 2 O 3 ) was synthesized by nanocasting technique, in which highly ordered mesoporous silca (SBA-15) was used as structural matrix. X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM) Brunauer-Emmett-Teller (BET) and Barrett-Joyner-Halanda (BJH) studies were carried out on m-In 2 O 3 and the results revealed that this material has a highly ordered mesoporous surface with reduced grain size, increased surface area and surface volume compared to the non porous indium oxide. The diffuse reluctance spectrum exhibited substantially improved light absorption efficiency in m-In 2 O 3 compared to normal indium oxide, however, no considerable change in the band gap energies of these materials was observed. When m-In 2 O 3 was used as a photo-catalyst in the photo-catalytic process of converting carbon dioxide (CO 2 ) into methanol under the pulsed laser radiation of 266-nm wavelengths, an enhanced photo-catalytic activity with the quantum efficiency of 4.5% and conversion efficiency of 46.3% were observed. It was found that the methanol production yield in this chemical process is as high as 485 µlg -1 h -1 after 150 min of irradiation, which is substantially higher than the yields reported in the literature. It is quite clear from the results that the introduction of mesoporosity in indium oxide, and the consequent enhancement of positive attributes required for a photo-catalyst, transformed photo-catalytically weak indium oxide into an effective photo-catalyst for the conversion of CO 2 into methanol.

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

NASA Astrophysics Data System (ADS)

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

2018-03-01

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

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

NASA Astrophysics Data System (ADS)

Gunathilake, Chamila Asanka

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

Dynamic and structural properties of room-temperature ionic liquids near silica and carbon surfaces.

PubMed

Li, Song; Han, Kee Sung; Feng, Guang; Hagaman, Edward W; Vlcek, Lukas; Cummings, Peter T

2013-08-06

The dynamic and structural properties of a room-temperature ionic liquid (RTIL) 1-butyl-3-methyl-imidazolium(trifluoromethanesulfonimide) ([C4mim][Tf2N]) confined in silica and carbon mesopores were investigated by molecular dynamics (MD) simulations and nuclear magnetic resonance (NMR) experiments. The complex interfacial microstructures of confined [C4mim][Tf2N] are attributed to the distinctive surface features of the silica mesopore. The temperature-dependent diffusion coefficients of [C4mim][Tf2N] confined in the silica or carbon mesopore exhibit divergent behavior. The loading fraction (f = 1.0, 0.5, and 0.25) has a large effect on the magnitude of the diffusion coefficient in the silica pore and displays weaker temperature dependence as the loading fraction decreases. The diffusion coefficients of mesoporous carbon-confined [C4mim][Tf2N] are relatively insensitive to the loading faction and exhibit a temperature dependence that is similar to the bulk dependence at all loading levels. Such phenomena can be attributed to the unique surface heterogeneity, dissimilar interfacial microstructures, and interaction potential profile of RTILs near silica and carbon walls.

Controllable synthesis of nitrogen-doped hollow mesoporous carbon spheres using ionic liquids as template for supercapacitors

NASA Astrophysics Data System (ADS)

Chen, Aibing; Li, Yunqian; Liu, Lei; Yu, Yifeng; Xia, Kechan; Wang, Yuying; Li, Shuhui

2017-01-01

We have demonstrated a facile and controllable synthesis of monodispersed nitrogen-doped hollow mesoporous carbon spheres (N-HMCSs) using resorcinol/formaldehyde resin as a carbon precursor, tetraethyl orthosilicate as a structure-assistant agent, ionic liquids (ILs) as soft template, partial carbon sources, and nitrogen sources. The sizes and the architectures including hollow and yolk-shell of resultant carbon spheres can be efficiently controlled through the adjustment of the content of ILs. Alkyl chain length of the ILs also has an important effect on the formation of N-HMCSs. With proper alkyl chain length and content of ILs, the resultant N-HMCSs show monodispersed hollow spheres with high surface areas (up to 1158 m2 g-1), large pore volumes (up to 1.70 cm3 g-1), and uniform mesopore size (5.0 nm). Combining the hollow mesoporous structure, high porosity, large surface area, and nitrogen functionality, the as-synthesized N-HMCSs have good supercapacitor performance with good capacitance (up to 159 F g-1) and favorable capacitance retention (88% capacitive retention after 5000 cycles).

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

NASA Astrophysics Data System (ADS)

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

2016-04-01

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

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

PubMed

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

2014-12-25

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.

Nitrogen-doped mesoporous carbon-armored cobalt nanoparticles as efficient hydrogen evolving electrocatalysts.

PubMed

Tang, Duihai; Li, Kuo; Zhang, Wenting; Qiao, Zhen-An; Zhu, Junjiang; Zhao, Zhen

2018-03-15

A series of Co nanoparticles embedded, N-doped mesoporous carbons have been synthesized through chelate-assisted co-assembly strategy followed by thermal treatment. The preparation is based on an assembly process, with evaporation of an ethanol-water solution containing melamine formaldehyde resin (MF resin) as carbon source, nitrogen source, and chelating agent. Moreover, F127 and Co(NO 3 ) 2 are used as template and metallic precursor, respectively. The Co nanoparticles embedded, N-doped mesoporous carbon annealed at 800 °C (denoted as MFCo800) shows high electrocatalytic activity for hydrogen evolution reaction (HER) with high current density and low overpotential, which has the ability to operate in both acidic and alkaline electrolytes. Copyright © 2017. Published by Elsevier Inc.

Bismuth oxyfluoride @ CMK-3 nanocomposite as cathode for lithium ion batteries

NASA Astrophysics Data System (ADS)

Ni, Dan; Sun, Wang; Xie, Liqiang; Fan, Qinghua; Wang, Zhenhua; Sun, Kening

2018-01-01

Bismuth oxyfluoride impregnated CMK-3 nanocomposite is synthesized by a facile nanocasting approach. Mesoporous carbon CMK-3 can suppress the aggregation and growth of bismuth oxyfluoride particles and offer rapid electron and Li ion passageways. Bismuth oxyfluoride nanoparticles are embedded in the mesoporous channels with particle size less than 20 nm. The bismuth oxyfluoride@CMK-3 nanocomposite maintains 148 mA h g-1 after 40 cycles with the capacity from both the bismuth oxyfluoride and the functional groups on the mesoporous carbon. The hybrid with confined bismuth oxyfluoride nanoparticles, conductive carbon network, and oxygen functional groups on the carbon matrix exhibits higher capacity and cycling stability than bulk bismuth oxyfluoride particles when used as lithium ion batteries cathode.

A high-performance mesoporous carbon supported nitrogen-doped carbon electrocatalyst for oxygen reduction reaction

NASA Astrophysics Data System (ADS)

Xu, Jingjing; Lu, Shiyao; Chen, Xu; Wang, Jianan; Zhang, Bo; Zhang, Xinyu; Xiao, Chunhui; Ding, Shujiang

2017-12-01

Investigating low-cost and highly active electrocatalysts for oxygen reduction reactions (ORR) is of crucial importance for energy conversion and storage devices. Herein, we design and prepare mesoporous carbon supported nitrogen-doped carbon by pyrolysis of polyaniline coated on CMK-3. This electrocatalyst exhibits excellent performance towards ORR in alkaline media. The optimized nitrogen-doped mesoporous electrocatalyst show an onset potential (E onset) of 0.95 V (versus reversible hydrogen electrode (RHE)) and half-wave potential (E 1/2) of 0.83 V (versus RHE) in 0.1 M KOH. Furthermore, the as-prepared catalyst presents superior durability and methanol tolerance compared to commercial Pt/C indicating its potential applications in fuel cells and metal-air batteries.

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

PubMed

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

2017-01-11

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

General Method for the Synthesis of Hollow Mesoporous Carbon Spheres with Tunable Textural Properties.

PubMed

Mezzavilla, Stefano; Baldizzone, Claudio; Mayrhofer, Karl J J; Schüth, Ferdi

2015-06-17

A versatile synthetic procedure to prepare hollow mesoporous carbon spheres (HMCS) is presented here. This approach is based on the deposition of a homogeneous hybrid polymer/silica composite shell on the outer surface of silica spheres through the surfactant-assisted simultaneous polycondensation of silica and polymer precursors in a colloidal suspension. Such composite materials can be further processed to give hollow mesoporous carbon spheres. The flexibility of this method allows for independent control of the morphological (i.e., core diameter and shell thickness) and textural features of the carbon spheres. In particular, it is demonstrated that the size of the pores within the mesoporous shell can be precisely tailored over an extended range (2-20 nm) by simply adjusting the reaction conditions. In a similar fashion, also the specific carbon surface area as well as the total shell porosity can be tuned. Most importantly, the textural features can be adjusted without affecting the dimension or the morphology of the spheres. The possibility to directly modify the shell textural properties by varying the synthetic parameters in a scalable process represents a distinct asset over the multistep hard-templating (nanocasting) routes. As an exemplary application, Pt nanoparticles were encapsulated in the mesoporous shell of HMCS. The resulting Pt@HMCS catalyst showed an enhanced stability during the oxygen reduction reaction, one of the most important reactions in electrocatalysis. This new synthetic procedure could allow the expansion, perhaps even beyond the lab-scale, of advanced carbon nanostructured supports for applications in catalysis.

Highly Loaded Mesoporous Silica/Nanoparticle Composites and Patterned Mesoporous Silica Films

NASA Astrophysics Data System (ADS)

Kothari, Rohit; Hendricks, Nicholas R.; Wang, Xinyu; Watkins, James J.

2014-03-01

Novel approaches for the preparation of highly filled mesoporous silica/nanoparticle (MS/NP) composites and for the fabrication of patterned MS films are described. The incorporation of iron platinum NPs within the walls of MS is achieved at high NP loadings by doping amphiphilic poly(ethylene oxide-b-propylene oxide-b-ethylene oxide) (Pluronic®) copolymer templates via selective hydrogen bonding between the pre-synthesized NPs and the hydrophilic portion of the block copolymer. The MS is then synthesized by means of phase selective condensation of tetraethylorthosilicate (TEOS) within the NP loaded block copolymer templates dilated with supercritical carbon dioxide (scCO2) followed by calcination. For patterned films, microphase separated block copolymer/small molecule additive blends are patterned using UV-assisted nanoimprint lithography. Infusion and condensation of a TEOS within template films using ScCO2 as a processing medium followed by calcination yields the patterned MS films. Scanning electron microscopy is used characterize pattern fidelity and transmission electron microscopy analysis confirms the presence of the mesopores. Long range order in nanocomposites is confirmed by low angle x-ray diffraction.

Highly efficient synthesis of ordered nitrogen-doped mesoporous carbons with tunable properties and its application in high performance supercapacitors

NASA Astrophysics Data System (ADS)

Liu, Dan; Zeng, Chao; Qu, Deyu; Tang, Haolin; Li, Yu; Su, Bao-Lian; Qu, Deyang

2016-07-01

Nitrogen-doped ordered mesoporous carbons (OMCs) have been synthesized via aqueous cooperative assembly route in the presence of basic amino acids as either polymerization catalysts or nitrogen dopants. This method allows the large-scale production of nitrogen-doped OMCs with tunable composition, structure and morphology while maintaining highly ordered mesostructures. For instances, the nitrogen content can be varied from ∼1 wt% to ∼6.3 wt% and the mesophase can be either 3-D body-centered cubic or 2-D hexagonal. The specific surface area for typical OMCs is around 600 m2 g-1, and further KOH activation can significantly enhance the surface area to 1866 m2 g-1 without destroying the ordered mesostructures. Benefiting from hierarchically ordered porous structure, nitrogen-doping effect and large-scale production availability, the synthesized OMCs show a great potential towards supercapacitor application. When measured in a symmetrical two-electrode configuration with an areal mass loading of ∼3 mg cm-2, the activated OMC exhibits high capacitance (186 F g-1 at 0.25 A g-1) and good rate capability (75% capacity retention at 20 A g-1) in ionic liquid electrolyte. Even as the mass loading is up to ∼12 mg cm-2, the OMC electrode still yields a specific capacitance of 126 F g-1 at 20 A g-1.

A highly efficient electrocatalyst for oxygen reduction reaction: phosphorus and nitrogen co-doped hierarchically ordered porous carbon derived from an iron-functionalized polymer

NASA Astrophysics Data System (ADS)

Deng, Chengwei; Zhong, Hexiang; Li, Xianfeng; Yao, Lan; Zhang, Huamin

2016-01-01

Heteroatom-doped carbon materials have shown respectable activity for the oxygen reduction reaction (ORR) in alkaline media. However, the performances of these materials are not satisfactory for energy conversion devices, such as fuel cells. Here, we demonstrate a new type of phosphorus and nitrogen co-doped hierarchically ordered porous carbon (PNHOPC) derived from an iron-functionalized mesoporous polymer through an evaporation-induced self-assembly process that simultaneously combines the carbonization and nitrogen doping processes. The soft template and the nitrogen doping process facilitate the formation of the hierarchically ordered structure for the PNHOPC. The catalyst possesses a large surface area (1118 cm2 g-1) and a pore volume of 1.14 cm3 g-1. Notably, it exhibits excellent ORR catalytic performance, superior stability and methanol tolerance in acidic electrolytes, thus making the catalyst promising for fuel cells. The correlations between the unique pore structure and the nitrogen and phosphorus configuration of the catalysts with high catalytic activity are thoroughly investigated.Heteroatom-doped carbon materials have shown respectable activity for the oxygen reduction reaction (ORR) in alkaline media. However, the performances of these materials are not satisfactory for energy conversion devices, such as fuel cells. Here, we demonstrate a new type of phosphorus and nitrogen co-doped hierarchically ordered porous carbon (PNHOPC) derived from an iron-functionalized mesoporous polymer through an evaporation-induced self-assembly process that simultaneously combines the carbonization and nitrogen doping processes. The soft template and the nitrogen doping process facilitate the formation of the hierarchically ordered structure for the PNHOPC. The catalyst possesses a large surface area (1118 cm2 g-1) and a pore volume of 1.14 cm3 g-1. Notably, it exhibits excellent ORR catalytic performance, superior stability and methanol tolerance in acidic electrolytes, thus making the catalyst promising for fuel cells. The correlations between the unique pore structure and the nitrogen and phosphorus configuration of the catalysts with high catalytic activity are thoroughly investigated. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr06749a

High-Performance Li-Ion Capacitor Based on an Activated Carbon Cathode and Well-Dispersed Ultrafine TiO2 Nanoparticles Embedded in Mesoporous Carbon Nanofibers Anode.

PubMed

Yang, Cheng; Lan, Jin-Le; Liu, Wen-Xiao; Liu, Yuan; Yu, Yun-Hua; Yang, Xiao-Ping

2017-06-07

A novel Li-ion capacitor based on an activated carbon cathode and a well-dispersed ultrafine TiO 2 nanoparticles embedded in mesoporous carbon nanofibers (TiO 2 @PCNFs) anode was reported. A series of TiO 2 @PCNFs anode materials were prepared via a scalable electrospinning method followed by carbonization and a postetching method. The size of TiO 2 nanoparticles and the mesoporous structure of the TiO 2 @PCNFs were tuned by varying amounts of tetraethyl orthosilicate (TEOS) to increase the energy density and power density of the LIC significantly. Such a subtle designed LIC displayed a high energy density of 67.4 Wh kg -1 at a power density of 75 W kg -1 . Meanwhile, even when the power density was increased to 5 kW kg -1 , the energy density can still maintain 27.5 Wh kg -1 . Moreover, the LIC displayed a high capacitance retention of 80.5% after 10000 cycles at 10 A g -1 . The outstanding electrochemical performance can be contributed to the synergistic effect of the well-dispersed ultrafine TiO 2 nanoparticles, the abundant mesoporous structure, and the conductive carbon networks.

Mesoporous activated coconut shell-derived hydrochar prepared via hydrothermal carbonization-NaOH activation for methylene blue adsorption.

PubMed

Islam, Md Azharul; Ahmed, M J; Khanday, W A; Asif, M; Hameed, B H

2017-12-01

Mesoporous activated carbon was prepared using a hydrochar derived from coconut shell waste through hydrothermal carbonization and NaOH chemical activation process (COSHTC). Three sets of activated carbons were obtained with different hydrochar:NaOH impregnation ratios (1:1, 1:2, and 1:3). Among these ratios, 1:3 (COSHTC3) exhibited the optimum adsorption for methylene blue (MB). COSHTC3 adsorbed MB with an initial concentration of 25-250 mg/L at pH 3-11 and 30 °C. The adsorption isotherm of MB on COSHTC3 demonstrated that Langmuir isotherm could be better applied at a maximum monolayer adsorption capacity of 200.01 mg/g at 30 °C. The data was well fitted to the pseudo-second-order (PSO) kinetic model. These results show that the COSHTC3 prepared from low-cost agricultural waste (coconut shell) with average pore diameter 28.6 Å and surface area 876.14 m 2 /g acts as a better adsorbent for removal of cationic dyes and could pave the way for more low-cost adsorbents for dye removal. Copyright © 2017 Elsevier Ltd. All rights reserved.

Adsorption dynamics of methyl violet onto granulated mesoporous carbon: Facile synthesis and adsorption kinetics.

PubMed

Kim, Yohan; Bae, Jiyeol; Park, Hosik; Suh, Jeong-Kwon; You, Young-Woo; Choi, Heechul

2016-09-15

A new and facile one-step synthesis method for preparing granulated mesoporous carbon (GMC) with three-dimensional spherical mesoporous symmetry is prepared to remove large molecular weight organic compounds in aqueous phase. GMC is synthesized in a single step using as-synthesized mesoporous carbon particles and organic binders through a simple and economical synthesis approach involving a simultaneous calcination and carbonization process. Characterization results obtained from SEM, XRD, as well as surface and porosity analysis indicate that the synthesized GMC has similar physical properties to those of the powdered mesoporous carbon and maintains the Brunauer-Emmett-Teller (BET) surface area and pore volume because the new synthesis method prevents the collapse of the pores during the granulation process. Batch adsorption experiments revealed GMC showed a substantial adsorption capacity (202.8 mg/g) for the removal of methyl violet as a target large molecular contaminant in aqueous phase. The mechanisms and dynamics modeling of GMC adsorption were also fully examined, which revealed that surface diffusion was rate limiting step on adsorption process of GMC. Adsorption kinetics of GMC enables 3 times faster than that of granular activated carbon in terms of surface diffusion coefficient. This is the first study, to the best of our knowledge, to synthesize GMC as an adsorbent for water purification by using facile granulation method and to investigate the adsorption kinetics and characteristics of GMC. This study introduces a new and simple method for the synthesis of GMC and reveals its adsorption characteristics for large molecular compounds in a water treatment. Copyright © 2016 Elsevier Ltd. All rights reserved.

Facile ionothermal synthesis of microporous and mesoporous carbons from task specific ionic liquids.

PubMed

Lee, Je Seung; Wang, Xiqing; Luo, Huimin; Baker, Gary A; Dai, Sheng

2009-04-08

An expedient, template-free, high-yield, and solventless route to nitrogen-rich micro- and mesoporous carbons is reported based on direct, atmospheric-pressure carbonization of task-specific ionic liquids bearing one or more nitrile side chains. The resulting textural properties (pore regime, surface area) are highly dependent upon the structural motifs of the ions comprising the corresponding parent ionic liquid, and uniform carbon films are routinely deposited with this novel methodology, highlighting excited new opportunities in the development of advanced functional carbon composites.

"Egg-Box"-Assisted Fabrication of Porous Carbon with Small Mesopores for High-Rate Electric Double Layer Capacitors.

PubMed

Kang, Danmiao; Liu, Qinglei; Gu, Jiajun; Su, Yishi; Zhang, Wang; Zhang, Di

2015-11-24

Here we report a method to fabricate porous carbon with small mesopores around 2-4 nm by simple activation of charcoals derived from carbonization of seaweed consisting of microcrystalline domains formed by the "egg-box" model. The existence of mesopores in charcoals leads to a high specific surface area up to 3270 m(2) g(-1), with 95% surface area provided by small mesopores. This special pore structure shows high adaptability when used as electrode materials for an electric double layer capacitor, especially at high charge-discharge rate. The gravimetric capacitance values of the porous carbon are 425 and 210 F g(-1) and volumetric capacitance values are 242 and 120 F cm(-3) in 1 M H2SO4 and 1 M TEA BF4/AN, respectively. The capacitances even remain at 280 F g(-1) (160 F cm(-3)) at 100 A g(-1) and 156 F g(-1) (90 F cm(-3)) at 50 A g(-1) in the aqueous and organic electrolytes, demonstrating excellent high-rate capacitive performance.

Mesoporous wormholelike carbon with controllable nanostructure for lithium ion batteries application

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

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

2015-06-15

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

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

NASA Astrophysics Data System (ADS)

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

2015-10-01

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

Facile one-pot synthesis and characterization of nickel supported on hierarchically porous carbon

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

Kotbagi, Trupti V.; Hakat, Yasemin; Bakker, Martin G., E-mail: Bakker@ua.edu

2016-01-15

Highlights: • Novel, inexpensive, one-pot, synthesis method for Ni on hierarchically porous carbon. • Disappearance of surfactant mesopores seen with incorporation of nickel. • Distribution of Ni nanoparticles on the hierarchically porous carbon support was studied by SEM. • Nickel nanoparticles were dispersed on macropore walls and not within carbon. - Abstract: Described is a novel, facile route for the synthesis of nickel supported on hierarchically porous carbon (Ni/HPC) using a one-pot co-gelation sol–gel method. Ni/HPC with varying nickel loadings (0.5, 1, 2.5 and 5 wt% Ni) were synthesized and the materials characterized by nitrogen physisorption, X-ray diffraction (XRD), scanningmore » electron microscopy (SEM), and Fourier transform infrared (FTIR) and Raman spectroscopies. The results show a three-dimensional network of disordered carbon with fine nickel nanoparticles of sizes ranging from 8 nm to 13 nm at 0.5 wt% Ni loading which gradually increased with increase in the Ni loading. The carbon structure was retained at the macropore level, but not at the mesoscale where the ordered mesopores were lost on nickel addition. The nickel nanoparticles were observed to grow on the surface of the ligaments. This may make them particularly suitable for low pressure Ni-catalyzed organic transformations e.g., hydrogenations, C–C coupling, C-heteroatom coupling, etc.« less

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

NASA Astrophysics Data System (ADS)

Yang, Xiaoqing; Li, Chengfei; Fu, Ruowen

2016-07-01

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

Metal-nitrogen doping of mesoporous carbon/graphene nanosheets by self-templating for oxygen reduction electrocatalysts.

PubMed

Li, Shuang; Wu, Dongqing; Liang, Haiwei; Wang, Jinzuan; Zhuang, Xiaodong; Mai, Yiyong; Su, Yuezeng; Feng, Xinliang

2014-11-01

We demonstrate a general and efficient self-templating strategy towards transition metal-nitrogen containing mesoporous carbon/graphene nanosheets with a unique two-dimensional (2D) morphology and tunable mesoscale porosity. Owing to the well-defined 2D morphology, nanometer-scale thickness, high specific surface area, and the simultaneous doping of the metal-nitrogen compounds, the as-prepared catalysts exhibits excellent electrocatalytic activity and stability towards the oxygen reduction reaction (ORR) in both alkaline and acidic media. More importantly, such a self-templating approach towards two-dimensional porous carbon hybrids with diverse metal-nitrogen doping opens up new avenues to mesoporous heteroatom-doped carbon materials as electrochemical catalysts for oxygen reduction and hydrogen evolution, with promising applications in fuel cell and battery technologies. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

PubMed

Lin, Yi-Feng; Chen, Jia-Ling

2014-04-15

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. Copyright © 2014 Elsevier Inc. All rights reserved.

High performance activated carbon for benzene/toluene adsorption from industrial wastewater.

PubMed

Asenjo, Natalia G; Alvarez, Patricia; Granda, Marcos; Blanco, Clara; Santamaría, Ricardo; Menéndez, Rosa

2011-09-15

A coal-tar-derived mesophase was chemically activated to produce a high surface area (~3200 m(2)/g) carbon with a porosity made up of both micropores and mesopores. Its adsorption capacities were found to be among the highest ever reported in literature, reaching values of 860 mg/g and 1200 mg/g for the adsorption of benzene and toluene, respectively, and 1200 mg/g for the combined adsorption of benzene and toluene from an industrial wastewater. Such high values imply that the entire pore system, including the mesopore fraction, is involved in the adsorption process. The almost complete pore filling is thought to be due to the high relative concentrations of the tested solutions, resulting from the low saturation concentration values for benzene and toluene, which were obtained by fitting the adsorption data to the BET equation in liquid phase. The kinetics of adsorption in the batch experiments which were conducted in a syringe-like adsorption chamber was observed to proceed in accordance with the pseudo-second order kinetic model. The combined presence of micropores and mesopores in the material is thought to be the key to the high kinetic performance, which was outstanding in a comparison with other porous materials reported in the literature. Copyright © 2011 Elsevier B.V. All rights reserved.

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

PubMed

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

2010-06-15

In this paper the direct electrochemistry of double-stranded DNA (dsDNA) was investigated on ordered mesoporous carbon (OMC) modified carbon ionic liquid electrode (CILE). CILE was prepared by mixing graphite powder with 1-ethyl-3-methylimidazolium ethylsulphate ([EMIM]EtOSO(3)) and liquid paraffin. A stable OMC film was formed on the surface of CILE with the help of Nafion to get a modified electrode denoted as Nafion-OMC/CILE. Due to the specific characteristics of OMC and IL present on the electrode surface, the fabricated electrode showed good electrochemical performances to different electroactive molecules. The electrochemical responses of dsDNA were carefully investigated on this electrode with two irreversible oxidation peak appeared at +1.250 V and +0.921 V (vs. SCE), which was corresponding to the oxidation of adenine and guanine residues in dsDNA structure. The electrochemical behaviors of dsDNA were carefully investigated on the Nafion-OMC/CILE. Experimental results indicated that the electron transfer rate was promoted with the increase of the oxidation peak current and the decrease of the oxidation peak potential, which was due to the electrocatalytic ability of OMC on the electrode surface. Under the optimal conditions the oxidation peak current increased with dsDNA concentration in the range of 10.0-600.0 microg mL(-1) by differential pulse voltammetry (DPV) with the detection limit of 1.2 microg mL(-1) (3sigma). Copyright 2010 Elsevier B.V. All rights reserved.

Fabrication of Nitrogen-Doped Hollow Mesoporous Spherical Carbon Capsules for Supercapacitors.

PubMed

Chen, Aibing; Xia, Kechan; Zhang, Linsong; Yu, Yifeng; Li, Yuetong; Sun, Hexu; Wang, Yuying; Li, Yunqian; Li, Shuhui

2016-09-06

A novel "dissolution-capture" method for the fabrication of nitrogen-doped hollow mesoporous spherical carbon capsules (N-HMSCCs) with high capability for supercapacitor is developed. The fabrication process is performed by depositing mesoporous silica on the surface of the polyacrylonitrile nanospheres, followed by a dissolution-capture process occurring in the polyacrylonitrile core and silica shell. The polyacrylonitrile core is dissolved by dimethylformamide treatment to form a hollow cavity. Then, the polyacrylonitrile is captured into the mesochannel of silica. After carbonization and etching of silica, N-HMSCCs with uniform mesopore size are produced. The N-HMSCCs show a high specific capacitance of 206.0 F g(-1) at a current density of 1 A g(-1) in 6.0 M KOH due to its unique hollow nanostructure, high surface area, and nitrogen content. In addition, 92.3% of the capacitance of N-HMSCCs still remains after 3000 cycles at 5 A g(-1). The "dissolution-capture" method should give a useful enlightenment for the design of electrode materials for supercapacitor.

Enhancement of oxygen reduction reaction activities by Pt nanoclusters decorated on ordered mesoporous porphyrinic carbons

DOE PAGES

Sun-Mi Hwang; Choi, YongMan; Kim, Min Gyu; ...

2016-03-08

The high cost of Pt-based membrane electrode assemblies (MEAs) is a critical hurdle for the commercialization of polymer electrolyte fuel cells (PEFCs). Recently, non-precious metal-based catalysts (NPMCs) have demonstrated much enhanced activity but their oxygen reduction reaction (ORR) activity is still inferior to that of Pt-based catalysts resulting in a much thicker electrode in the MEA. For the reduction of mass transport and ohmic overpotential we adopted a new concept of catalyst that combines an ultra-low amount of Pt nanoclusters with metal–nitrogen (M–Nx) doped ordered mesoporous porphyrinic carbon (FeCo–OMPC(L)). The 5 wt% Pt/FeCo–OMPC(L) showed a 2-fold enhancement in activities comparedmore » to a higher loading of Pt. Our experimental results supported by first-principles calculations indicate that a trace amount of Pt nanoclusters on FeCo–OMPC(L) significantly enhances the ORR activity due to their electronic effect as well as geometric effect from the reduced active sites. Finally, in terms of fuel cell commercialization, this class of catalysts is a promising candidate due to the limited use of Pt in the MEA.« less

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

NASA Astrophysics Data System (ADS)

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

2013-12-01

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

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

PubMed

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

2016-08-01

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

Highly ordered mesoporous carbons as electrode material for the construction of electrochemical dehydrogenase- and oxidase-based biosensors.

PubMed

Zhou, Ming; Shang, Li; Li, Bingling; Huang, Lijian; Dong, Shaojun

2008-11-15

In this work, the excellent catalytic activity of highly ordered mesoporous carbons (OMCs) to the electrooxidation of nicotinamide adenine dinucleotide (NADH) and hydrogen peroxide (H(2)O(2)) was described for the construction of electrochemical alcohol dehydrogenase (ADH) and glucose oxidase (GOD)-based biosensors. The high density of edge-plane-like defective sites and high specific surface area of OMCs could be responsible for the electrocatalytic behavior at OMCs modified glassy carbon electrode (OMCs/GE), which induced a substantial decrease in the overpotential of NADH and H(2)O(2) oxidation reaction compared to carbon nanotubes modified glassy carbon electrode (CNTs/GE). Such ability of OMCs permits effective low-potential amperometric biosensing of ethanol and glucose, respectively, at Nafion/ADH-OMCs/GE and Nafion/GOD-OMCs/GE. Especially, as an amperometric glucose biosensor, Nafion/GOD-OMCs/GE showed large determination range (500-15,000 micromoll(-1)), high sensitivity (0.053 nA micromol(-1)), fast (9+/-1s) and stable response (amperometric response retained 90% of the initial activity after 10h stirring of 2 mmoll(-1) glucose solution) to glucose as well as the effective discrimination to the possible interferences, which may make it to readily satisfy the need for the routine clinical diagnosis of diabetes. By comparing the electrochemical performance of OMCs with that of CNTs as electrode material for the construction of ADH- and GOD-biosensors in this work, we reveal that OMCs could be a favorable and promising carbon electrode material for constructing other electrochemical dehydrogenase- and oxidase-based biosensors, which may have wide potential applications in biocatalysis, bioelectronics and biofuel cells.

Facile Fabrication of Composition-Tuned Ru-Ni Bimetallics in Ordered Mesoporous Carbon for Levulinic Acid Hydrogenation

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

Yang, Ying; Gao, Guang; Zhang, Xin

Bimetallic catalysts are of great importance due to their unique catalytic properties. However, their conventional synthesis requires tedious multistep procedures and prolonged synthetic time, and the resulting bimetallics usually disperse unevenly and show poor stability. It is challenging to develop a facile and step-economic synthetic methodology for highly efficient bimetallic catalysts. In this study, we report an elegant metal complex-involved multicomponent assembly route to highly efficient Ru–Ni bimetallics in ordered mesoporous carbons (OMC). The fabrication of composition-tuned Ru–Ni bimetallics in OMC (Ru xNi 1–x–OMC, x = 0.5–0.9) was facilely realized via in situ construction of CTAB-directed cubic Ia3d chitosan-ruthenium–nickel–silica mesophasemore » before pyrolysis and silica removal. The resulting Ru xNi 1–x–OMC materials are in-depth characterized with X-ray diffraction, N 2 adsorption–desorption, transmission electron microscopy, infrared spectrum, and X-ray absorption fine structure. This facile fabrication method renders homogeneously dispersed Ru–Ni bimetallics embedded in the mesoporous carbonaceous framework and creates a highly active and stable Ru 0.9Ni 0.1–OMC catalyst for the hydrogenation of levulinic acid (LA) to prepare γ-valerolactone (GVL), a biomass-derived platform molecule with wide application in the preparation of renewable chemicals and liquid transportation fuels. A high TOF (>2000 h –1) was obtained, and the Ru 0.9Ni 0.1–OMC catalyst could be used at least 15 times without obvious loss of its catalytic performance.« less

Physicochemical and adsorptive characteristics of activated carbons from waste polyester textiles utilizing MgO template method.

PubMed

Xu, Zhihua; Zhang, Daofang; Yuan, Zhihang; Chen, Weifang; Zhang, Tianqi; Tian, Danqi; Deng, Haixuan

2017-10-01

Activated carbons with high specific surface areas were produced, utilizing waste polyester textiles as carbon precursor by magnesium oxide (MgO) template method. Magnesium chloride (MgCl 2 ), magnesium citrate (MgCi), and MgO were employed as MgO precursors to prepare activated carbons (AC-MgCl 2 , AC-MgCi, and AC-MgO). Thermogravimetry-differential scanning calorimetry was conducted to investigate the pore-forming mechanism, and N 2 adsorption/desorption isotherms, XRD, SEM-EDS, TEM, FTIR and pH pzc were achieved to analyze physicochemical characteristics of the samples. The specific surface areas of AC-MgCl 2 (1173 m 2 /g) and AC-MgCi (1336 m 2 /g) were much higher than that of AC-MgO (450 m 2 /g), and the pores sizes of which were micro-mesoporous, mesoporous, and macropores, respectively, due to the formation of MgO crystal with different sizes. All activated carbons had abundant acidic oxygen groups. In addition, batch adsorption experiments were carried out to investigate the adsorptive characteristics of the prepared activated carbons toward Cr(VI). The adsorption kinetics fitted well with the pseudo-second order, and the adsorptive capacity of AC-MgCl 2 (42.55 mg/g) was higher than those of AC-MgCi (40.93 mg/g) and AC-MgO (35.87 mg/g).

Synthesis of Dispersible Mesoporous Nitrogen-Doped Hollow Carbon Nanoplates with Uniform Hexagonal Morphologies for Supercapacitors.

PubMed

Cao, Jie; Jafta, Charl J; Gong, Jiang; Ran, Qidi; Lin, Xianzhong; Félix, Roberto; Wilks, Regan G; Bär, Marcus; Yuan, Jiayin; Ballauff, Matthias; Lu, Yan

2016-11-02

In this study, dispersible mesoporous nitrogen-doped hollow carbon nanoplates have been synthesized as a new anisotropic carbon nanostructure using gibbsite nanoplates as templates. The gibbsite-silica core-shell nanoplates were first prepared before the gibbsite core was etched away. Dopamine as carbon precursor was self-polymerized on the hollow silica nanoplates surface assisted by sonification, which not only favors a homogeneous polymer coating on the nanoplates but also prevents their aggregation during the polymerization. Individual silica-polydopamine core-shell nanoplates were immobilized in a silica gel in an insulated state via a silica nanocasting technique. After pyrolysis in a nanoconfine environment and elimination of silica, discrete and dispersible hollow carbon nanoplates are obtained. The resulted hollow carbon nanoplates bear uniform hexagonal morphology with specific surface area of 460 m 2 ·g -1 and fairly accessible small mesopores (∼3.8 nm). They show excellent colloidal stability in aqueous media and are applied as electrode materials for symmetric supercapacitors. When using polyvinylimidazolium-based nanoparticles as a binder in electrodes, the hollow carbon nanoplates present superior performance in parallel to polyvinylidene fluoride (PVDF) binder.

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

PubMed

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

2014-01-21

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

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

PubMed

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

2014-08-15

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

Synergistic interaction and controllable active sites of nitrogen and sulfur co-doping into mesoporous carbon sphere for high performance oxygen reduction electrocatalysts

NASA Astrophysics Data System (ADS)

Oh, Taeseob; Kim, Myeongjin; Park, Dabin; Kim, Jooheon

2018-05-01

Nitrogen and sulfur co-doped mesoporous carbon sphere (NSMCS) was prepared as a metal-free catalyst by an economical and facile pyrolysis process. The mesoporous carbon spheres were derived from sodium carboxymethyl cellulose as the carbon source and the nitrogen and sulfur dopants were derived from urea and p-benzenedithiol, respectively. The doping level and chemical states of nitrogen and sulfur in the prepared NSMCS can be easily adjusted by controlling the pyrolysis temperature. The NSMCS pyrolyzed at 900 °C (NSMCS-900) exhibited higher oxygen reduction reaction activity than the mesoporous carbon sphere doped solely with nitrogen or sulfur, due to the synergistic effect of co-doping. Among all the NSMCS samples, NSMCS-900 exhibited excellent ORR catalytic activity owing to the presence of a highly active site, consisting of pyridinic N, graphitic N, and thiophene S. Remarkably, the NSMCS-900 catalyst was comparable with commercial Pt/C, in terms of the onset and the half-wave potentials and showed better durability than Pt/C for ORR in an alkaline electrolyte. The approach demonstrated in this work could be used to prepare promising metal-free electrocatalysts for application in energy conversion and storage.

Pyrolytic Synthesis of Carbon Nanotubes from Sucrose on a Mesoporous Silicate

NASA Technical Reports Server (NTRS)

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

2005-01-01

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

Preparation of novel oxidized mesoporous carbon with excellent adsorption performance for removal of malachite green and lead ion

NASA Astrophysics Data System (ADS)

Zhang, Xialan; Lin, Qilang; Luo, Shiyuan; Ruan, Kezhao; Peng, Kaiping

2018-06-01

An oxidized mesoporous carbon (OMC) with fluffy structure was fabricated from the mixture of petroleum asphalt and aluminum isopropoxide, and its structures were characterized by FESEM, TEM, BET, TG, XPS and FT-IR. In addition, bath absorption experiments for malachite green (MG) and lead ion (Pb2+) were carried out to explore the effects of pH, initial concentration, contact time and temperature on its absorption process. Results show that the OMC prepared has a fluffy ultrathin-wall structure with narrow pore size distribution and rich oxygen-containing groups. It exhibits excellent absorption performance for the removal of MG as well as Pb2+, as indicated by that its maximum adsorption capacity is 963.1 mg g-1 for MG and 198.6 mg g-1 for Pb2+. The absorption experimental data are all fitted well with pseudo-second-order model and Frendlich isotherm, respectively. More importantly, the OMC still maintains relatively high adsorption capacity after five cycles.

Acid-Functionalized Mesoporous Carbon: An Efficient Support for Ruthenium-Catalyzed γ-Valerolactone Production

DOE PAGES

Villa, Alberto; Schiavoni, Marco; Chan-Thaw, Carine E.; ...

2015-06-18

The hydrogenation of levulinic acid has been studied using Ru supported on ordered mesoporous carbons (OMCs) prepared by soft-templating. P- and S-containing acid groups were introduced by postsynthetic functionalization before the addition of 1% Ru by incipient wetness impregnation. These functionalities and the reaction conditions mediate the activity and selectivity of the levulinic acid hydrogenation. The presence of Scontaining groups (Ru/OMC-S and Ru/OMC-P/S) deactivates the Ru catalysts strongly, whereas the presence of P-containing groups (Ru/OMC-P) enhances the activity compared to that of pristine Ru/OMC. Under mild conditions (70 8C and 7 bar H2) the catalyst shows high selectivity to g-valerolactonemore » (GVL; >95%) and high stability on recycling. However, under more severe conditions (200 8C and pH2=40 bar) Ru/OMC-P is particularly able to promote GVL ring-opening and the consecutive hydrogenation to pentanoic acid.« less

Mesoporous-activated carbon prepared from chitosan flakes via single-step sodium hydroxide activation for the adsorption of methylene blue.

PubMed

Marrakchi, F; Ahmed, M J; Khanday, W A; Asif, M; Hameed, B H

2017-05-01

In this work, mesoporous-activated carbon (CSAC) was prepared from chitosan flakes (CS) via single-step sodium hydroxide activation for the adsorption of methylene blue (MB). CSAC was prepared using different impregnation ratios of NaOH:CS (1:1, 2:1, 3:1, and 4:1) at 800°C for 90min. The adsorption performance of CSAC was evaluated for MB at different adsorption variables, such MB initial concentrations (25-400mg/L), solution pH (3-11), and temperature (30-50°C). The adsorption isotherm data of CSAC-MB were well fitted to Langmuir model with a maximum adsorption capacity 143.53mg/g at 50°C. Best representation of kinetic data was obtained by the pseudo-second order model. CSAC exhibited excellent adsorption uptake for MB and can potentially be used for other cationic dyes. Copyright © 2017 Elsevier B.V. All rights reserved.

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

PubMed Central

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

2013-01-01

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

Electrochemical synthesis of mesoporous Pt-Au binary alloys with tunable compositions for enhancement of electrochemical performance.

PubMed

Yamauchi, Yusuke; Tonegawa, Akihisa; Komatsu, Masaki; Wang, Hongjing; Wang, Liang; Nemoto, Yoshihiro; Suzuki, Norihiro; Kuroda, Kazuyuki

2012-03-21

Mesoporous Pt-Au binary alloys were electrochemically synthesized from lyotropic liquid crystals (LLCs) containing corresponding metal species. Two-dimensional exagonally ordered LLC templates were prepared on conductive substrates from diluted surfactant solutions including water, a nonionic surfactant, ethanol, and metal species by drop-coating. Electrochemical synthesis using such LLC templates enabled the preparation of ordered mesoporous Pt-Au binary alloys without phase segregation. The framework composition in the mesoporous Pt-Au alloy was controlled simply by changing the compositional ratios in the precursor solution. Mesoporous Pt-Au alloys with low Au content exhibited well-ordered 2D hexagonal mesostructures, reflecting those of the original templates. With increasing Au content, however, the mesostructural order gradually decreased, thereby reducing the electrochemically active surface area. Wide-angle X-ray diffraction profiles, X-ray photoelectron spectra, and elemental mapping showed that both Pt and Au were atomically distributed in the frameworks. The electrochemical stability of mesoporous Pt-Au alloys toward methanol oxidation was highly improved relative to that of nonporous Pt and mesoporous Pt films, suggesting that mesoporous Pt-Au alloy films are potentially applicable as electrocatalysts for direct methanol fuel cells. Also, mesoporous Pt-Au alloy electrodes showed a highly sensitive amperometric response for glucose molecules, which will be useful in next-generation enzyme-free glucose sensors.

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

NASA Astrophysics Data System (ADS)

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

2017-10-01

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

High efficiency removal of triclosan by structure-directing agent modified mesoporous MIL-53(Al).

PubMed

Dou, Rongni; Zhang, Junya; Chen, Yuancai; Feng, Siyuan

2017-03-01

In order to expand the potential applications of metal-organic frameworks (MOFs), structure directing agents modified mesoporous MIL-53(Al) (MIL-53(Al)-1) was investigated to adsorb triclosan (TCS) with two different initial concentrations. MIL-53(Al)-1 with high mesoporosity and total pore volume exhibited higher adsorption capacity and 4.4 times faster adsorption of TCS at low concentration (1 mg L -1 ) than that of microporous MIL-53(Al). Also, mesoporous as well as microporous MIL-53(Al) showed significant higher adsorption capacity and two orders of magnitude greater fast uptake of TCS than two kinds of mesoporous-activated carbon. The adsorption of TCS onto MIL-53(Al)-1 released more energy and had higher disorderliness than TCS on MIL-53(Al). The superior adsorption characteristics of MIL-53(Al)-1 were preserved over a wide pH range (4-9), at high concentration of ionic strengths, and in the presence of coexisting compounds (anions, cations, phenol, aniline, and humic acid). The selectivity adsorption and Fourier transform infrared (FT-IR) spectra revealed that TCS adsorption on MIL-53(Al)s was mainly driven by hydrophobicity interaction assisted with hydrogen bonding on MIL-53(Al)s. MIL-53(Al)s can be effectively regenerated several times by washing with 90% methanol-water (pH 11). All of the above results demonstrated MIL-53(Al)s are promising adsorbents for water purification. Graphical abstract.

Correlation between mesopore volume of carbon supports and the immobilization of laccase from Trametes versicolor for the decolorization of Acid Orange 7.

PubMed

Ramírez-Montoya, Luis A; Hernández-Montoya, Virginia; Montes-Morán, Miguel A; Cervantes, Francisco J

2015-10-01

Immobilization of laccase from Trametes versicolor was carried out using carbon supports prepared from different lignocellulosic wastes. Enzymes were immobilized by physical adsorption. Taguchi methodology was selected for the design of experiments regarding the preparation of the carbon materials, which included the use of activating agents for the promotion of mesoporosity. A good correlation between the mesopore volumes of the carbon supports and the corresponding laccase loadings attained was observed. Specifically, the chemical activation of pecan nut shell with FeCl3 led to a highly mesoporous material that also behaved as the most efficient support for the immobilization of laccase. This particular laccase/carbon support system was used as biocatalyst for the decolorization of aqueous solutions containing Acid Orange 7. Mass spectrometry coupled to a liquid chromatograph allowed us to identify the products of the dye degradation. Copyright © 2015 Elsevier Ltd. All rights reserved.

Nitrogen--sulfur--carbon nanocomposites and their application as cathode materials in lithium--sulfur batteries

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

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

The invention is directed in a first aspect to electron-conducting porous compositions comprising an organic polymer matrix doped with nitrogen atoms and having elemental sulfur dispersed therein, particularly such compositions having an ordered framework structure. The invention is also directed to composites of such S/N-doped electron-conducting porous aromatic framework (PAF) compositions, or composites of an S/N-doped mesoporous carbon composition, which includes the S/N-doped composition in admixture with a binder, and optionally, conductive carbon. The invention is further directed to cathodes for a lithium-sulfur battery in which such composites are incorporated.

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

PubMed

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

2017-06-07

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

Adsorption of dyes by ACs prepared from waste tyre reinforcing fibre. Effect of texture, surface chemistry and pH.

PubMed

Acevedo, Beatriz; Rocha, Raquel P; Pereira, Manuel F R; Figueiredo, José L; Barriocanal, Carmen

2015-12-01

This paper compares the importance of the texture and surface chemistry of waste tyre activated carbons in the adsorption of commercial dyes. The adsorption of two commercial dyes, Basic Astrazon Yellow 7GLL and Reactive Rifafix Red 3BN on activated carbons made up of reinforcing fibres from tyre waste and low-rank bituminous coal was studied. The surface chemistry of activated carbons was modified by means of HCl-HNO3 treatment in order to increase the number of functional groups. Moreover, the influence of the pH on the process was also studied, this factor being of great importance due to the amphoteric characteristics of activated carbons. The activated carbons made with reinforcing fibre and coal had the highest SBET, but the reinforcing fibre activated carbon samples had the highest mesopore volume. The texture of the activated carbons was not modified upon acid oxidation treatment, unlike their surface chemistry which underwent considerable modification. The activated carbons made with a mixture of reinforcing fibre and coal experienced the largest degree of oxidation, and so had more acid surface groups. The adsorption of reactive dye was governed by the mesoporous volume, whilst surface chemistry played only a secondary role. However, the surface chemistry of the activated carbons and dispersive interactions played a key role in the adsorption of the basic dye. The adsorption of the reactive dye was more favored in a solution of pH 2, whereas the basic dye was adsorbed more easily in a solution of pH 12. Copyright © 2015 Elsevier Inc. All rights reserved.

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

PubMed

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

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. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis of magnetic CoFe2O4/ordered mesoporous carbon nanocomposites and application in Fenton-like oxidation of rhodamine B.

PubMed

Deng, Jing; Chen, Yi-Jing; Lu, Yu-An; Ma, Xiao-Yan; Feng, Shan-Fang; Gao, Naiyun; Li, Jun

2017-06-01

CoFe 2 O 4 /ordered mesoporous carbon (OMC) nanocomposites were synthesized and tested as heterogeneous peroxymonosulfate (PMS) activator for the removal of rhodamine B. Characterization confirmed that CoFe 2 O 4 nanoparticles were tightly bonded to OMC, and the hybrid catalyst possessed high surface area, pore volume, and superparamagnetism. Oxidation experiments demonstrated that CoFe 2 O 4 /OMC nanocomposites displayed favorable catalytic activity in PMS solution and rhodamine B degradation could be well described by pseudo-first-order kinetic model. Sulfate radicals (SO 4 - ·) were verified as the primary reactive species which was responsible for the decomposition of rhodamine B. The optimum loading ratio of CoFe 2 O 4 and OMC was determined to be 5:1. Under optimum operational condition (catalyst dosage 0.05 g/L, PMS concentration 1.5 mM, pH 7.0, and 25 °C), CoFe 2 O 4 /OMC-activated peroxymonosulfate system could achieve almost complete decolorization of 100 mg/L rhodamine B within 60 min. The enhanced catalytic activity of CoFe 2 O 4 /OMC nanocomposites compared to that of CoFe 2 O 4 nanoparticles could be attributable to the increased adsorption capacity and accelerated redox cycles between Co(III)/Co(II) and Fe(III)/Fe(II).

High surface area mesoporous activated carbon-alginate beads for efficient removal of methylene blue.

PubMed

Nasrullah, Asma; Bhat, A H; Naeem, Abdul; Isa, Mohamed Hasnain; Danish, Mohammed

2018-02-01

High surface area mesoporous activated carbon-alginate (AC-alginate) beads were successfully synthesized by entrapping activated carbon powder derived from Mangosteen fruit peel into calcium-alginate beads for methylene blue (MB) removal from aqueous solution. The structure and surface characteristics of AC-alginate beads were analyzed using Fourier transform infra-red (FTIR) spectroscopy, scanning electron microscopy (SEM) and surface area analysis (S BET ), while thermal properties were tested using thermogravimetric analysis (TGA). The effect of AC-alginate dose, pH of solution, contact time, initial concentration of MB solution and temperature on MB removal was elucidated. The results showed that the maximum adsorption capacity of 230mg/g was achieved for 100mg/L of MB solution at pH 9.5 and temperature 25°C. Furthermore, the adsorption of MB on AC-alginate beads followed well pseudo-second order equation and equilibrium adsorption data were better fitted by the Freundlich isotherm model. The findings reveal the feasibility of AC-alginate beads composite to be used as a potential and low cost adsorbent for removal of cationic dyes. Copyright © 2017 Elsevier B.V. All rights reserved.

Superior supercapacitors based on nitrogen and sulfur co-doped hierarchical porous carbon: Excellent rate capability and cycle stability

NASA Astrophysics Data System (ADS)

Zhang, Deyi; Han, Mei; Wang, Bing; Li, Yubing; Lei, Longyan; Wang, Kunjie; Wang, Yi; Zhang, Liang; Feng, Huixia

2017-08-01

Vastly improving the charge storage capability of supercapacitors without sacrificing their high power density and cycle performance would bring bright application prospect. Herein, we report a nitrogen and sulfur co-doped hierarchical porous carbon (NSHPC) with very superior capacitance performance fabricated by KOH activation of nitrogen and sulfur co-doped ordered mesoporous carbon (NSOMC). A high electrochemical double-layer (EDL) capacitance of 351 F g-1 was observed for the reported NSHPC electrodes, and the capacitance remains at 288 F g-1 even under a large current density of 20 A g-1. Besides the high specific capacitance and outstanding rate capability, symmetrical supercapacitor cell based on the NSHPC electrodes also exhibits an excellent cycling performance with 95.61% capacitance retention after 5000 times charge/discharge cycles. The large surface area caused by KOH activation (2056 m2 g-1) and high utilized surface area owing to the ideal micro/mesopores ratio (2.88), large micropores diameter (1.38 nm) and short opened micropores structure as well as the enhanced surface wettability induced by N and S heteroatoms doping and improved conductivity induced by KOH activation was found to be responsible for the very superior capacitance performance.

High-yield harvest of nanofibers/mesoporous carbon composite by pyrolysis of waste biomass and its application for high durability electrochemical energy storage.

PubMed

Liu, Wu-Jun; Tian, Ke; He, Yan-Rong; Jiang, Hong; Yu, Han-Qing

2014-12-02

Disposal and recycling of the large scale biomass waste is of great concern. Themochemically converting the waste biomass to functional carbon nanomaterials and bio-oil is an environmentally friendly apporach by reducing greenhouse gas emissions and air pollution caused by open burning. In this work, we reported a scalable, "green" method for the synthesis of the nanofibers/mesoporous carbon composites through pyrolysis of the Fe(III)-preloaded biomass, which is controllable by adjustment of temperature and additive of catalyst. It is found that the coupled catalytic action of both Fe and Cl species is able to effectively catalyze the growth of the carbon nanofibers on the mesoporous carbon and form magnetic nanofibers/mesoporous carbon composites (M-NMCCs). The mechanism for the growth of the nanofibers is proposed as an in situ vapor deposition process, and confirmed by the XRD and SEM results. M-NMCCs can be directly used as electrode materials for electrochemical energy storage without further separation, and exhibit favorable energy storage performance with high EDLC capacitance, good retention capability, and excellent stability and durability (more than 98% capacitance retention after 10,000 cycles). Considering that biomass is a naturally abundant and renewable resource (over billions tons biomass produced every year globally) and pyrolysis is a proven technique, M-NMCCs can be easily produced at large scale and become a sustainable and reliable resource for clean energy storage.

Facile and rapid one-pot microwave-assisted synthesis of Pd-Ni magnetic nanoalloys confined in mesoporous carbons

NASA Astrophysics Data System (ADS)

Martínez de Yuso, Alicia; Le Meins, Jean-Marc; Oumellal, Yassine; Paul-Boncour, Valérie; Zlotea, Claudia; Matei Ghimbeu, Camelia

2016-12-01

An easy and rapid one-pot microwave-assisted soft-template synthesis method for the preparation of Pd-Ni nanoalloys confined in mesoporous carbon is reported. This approach allows the formation of mesoporous carbon and the growth of the particles at the same time, under short microwave irradiation (4 h) compared to the several days spent for the classical approach. In addition, the synthesis steps are diminished and no thermopolymerization step or reduction treatment being required. The influence of the Pd-Ni composition on the particle size and on the carbon characteristics was investigated. Pd-Ni solid solutions in the whole composition range could be obtained, and the metallic composition proved to have an important effect on the nanoparticle size but low influence on carbon textural properties. Small and uniformly distributed nanoparticles were confined in mesoporous carbon with uniform pore size distribution, and dependence between the nanoparticle size and the nanoalloy composition was observed, i.e., increase of the particle size with increasing the Ni content (from 5 to 14 nm). The magnetic properties of the materials showed a strong nanoparticle size and/or composition effect. The blocking temperature of Pd-Ni nanoalloys increases with the increase of Ni amount and therefore of particle size. The magnetization values are smaller than the bulk counterpart particularly for the Ni-rich compositions due to the formed graphitic shells surrounding the particles inducing a dead magnetic layer.

[Adsorption kinetics and mechanism of lead (II) on polyamine-functionalized mesoporous activated carbon].

PubMed

Li, Kun-Quan; Wang, Yan-Jin; Yang, Mei-Rong; Zhu, Zhi-Qiang; Zheng, Zheng

2014-08-01

Bagasse mesoporous carbon was prepared by microwave assisted H3 PO4 activation. Amido and imido groups were modified with ethanediamine on the channels' surface of mesoporous carbon through nitric oxidation and amide reaction. The influence of Pb(II) concentration, adsorption time on Pb(II) adsorption on the ethanediamine-modified mesoporous carbon (AC-EDA) was investigated. The adsorption kinetics and mechanism were also discussed. The results showed that AC-EDA had a great performance for Pb(II) adsorption, and more than 70% of Pb(II) was adsorbed in 5 minutes. The adsorption amount of Pb(II) on the carbon increased with the increase of solution pH in acidic conditions. It was found that AC-EDA had different binding energies on different adsorption sites for Pb(II) separation. The Pb(II) adsorption process on AC-EDA was controlled by intra-particle diffusion in the first 3 min, and then film diffusion played the important pole on the adsorption. The adsorption amount increased with the increase of temperature, indicating the adsorption was an endothermic reaction. The high adsorption energy (> 11 kJ x mol(-1)) implied that the) adsorption was a chemical adsorption. The XPS of AC-EDA before and after Pb(II) adsorption showed that the polyamine group was involved in the adsorption, and should be a main factor of the high efficient adsorption.

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

PubMed

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

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. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

PubMed

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

2016-01-19

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

Recent Advances in the Separation of Rare Earth Elements Using Mesoporous Hybrid Materials.

PubMed

Hu, Yimu; Florek, Justyna; Larivière, Dominic; Fontaine, Frédéric-Georges; Kleitz, Freddy

2018-05-27

Over the past decades, the need for rare earth elements (REEs) has increased substantially, mostly because these elements are used as valuable additives in advanced technologies. However, the difference in ionic radius between neighboring REEs is small, which renders an efficient sized-based separation extremely challenging. Among different types of extraction methods, solid-phase extraction (SPE) is a promising candidate, featuring high enrichment factor, rapid adsorption kinetics, reduced solvent consumption and minimized waste generation. The great challenge remains yet to develop highly efficient and selective adsorbents for this process. In this regard, ordered mesoporous materials (OMMs) possess high specific surface area, tunable pore size, large pore volume, as well as stable and interconnected frameworks with active pore surfaces for functionalization. Such features meet the requirements for enhanced adsorbents, not only providing huge reactional interface and large surface capable of accommodating guest species, but also enabling the possibility of ion-specific binding for enrichment and separation purposes. This short personal account summarizes some of the recent advances in the use of porous hybrid materials as selective sorbents for REE separation and purification, with particular attention devoted to ordered mesoporous silica and carbon-based sorbents. © 2018 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

Electrochemical sensing platform based on the highly ordered mesoporous carbon-fullerene system.

PubMed

Zhou, Ming; Guo, Jidong; Guo, Li-ping; Bai, Jing

2008-06-15

In this paper, we report a novel all-carbon two-dimensionally ordered nanocomposite electrode system on the basis of the consideration of host-guest chemistry, which utilizes synergistic interactions between a nanostructured matrix of ordered mesoporous carbon (OMC) and an excellent electron acceptor of nanosized fullerene (C 60) to facilitate heterogeneous electron-transfer processes. The integration of OMC-C 60 by covalent interaction, especially its electrochemical applications for electrocatalysis, has not been explored thus far. Such integration may even appear to be counterintuitive because OMC and C 60 provide opposite electrochemical benefits in terms of facilitating heterogeneous electron-transfer processes. Nevertheless, the present work demonstrates the integration of OMC and C 60 can provide a remarkable synergistic augmentation of the current. To illuminate the concept, eight kinds of inorganic and organic electroactive compounds were employed to study the electrochemical response at an OMC-C 60 modified glassy carbon (OMC-C 60/GC) electrode for the first time, which shows more favorable electron-transfer kinetics than OMC/GC, carbon nanotube modified GC, C 60/GC, and GC electrodes. Such electrocatalytic behavior at OMC-C 60/GC electrode could be attributed to the unique physicochemical properties of OMC and C 60, especially the unusual host-guest synergy of OMC-C 60, which induced a substantial decrease in the overvoltage for NADH oxidation compared with GC electrode. The ability of OMC-C 60 to promote electron transfer not only suggests a new platform for the development of dehydrogenase-based bioelectrochemical devices but also indicates a potential of OMC-C 60 to be of a wide range of sensing applications because the electrocatalysis of different electroactive compounds at the OMC-C 60/GC electrode in this work should be a good model for constructing a novel and promising electrochemical sensing platform for further electrochemical detection of other biomolecules.

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

PubMed

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

2013-09-15

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. Copyright © 2013 Elsevier B.V. All rights reserved.

Adsorption of caffeine on mesoporous activated carbon fibers prepared from pineapple plant leaves.

PubMed

Beltrame, Karla K; Cazetta, André L; de Souza, Patrícia S C; Spessato, Lucas; Silva, Taís L; Almeida, Vitor C

2018-01-01

The present work reports the preparation of activated carbon fibers (ACFs) from pineapple plant leaves, and its application on caffeine (CFN) removal from aqueous solution. The preparation procedure was carried out using the H 3 PO 4 as activating agent and slow pyrolysis under N 2 atmosphere. The characterization of materials was performed from the N 2 adsorption and desorption isotherms, scanning electron microscopy (SEM), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Raman spectroscopy, Boehm titration and pH pzc method. ACFs showed high BET surface area value (S BET = 1031m 2 g -1 ), well-developed mesoporous structure (mesopore volume of 1.27cm³ g -1 ) and pores with average diameter (D M ) of 5.87nm. Additionally, ACFs showed features of fibrous material with predominance of acid groups on its surface. Adsorption studies indicated that the pseudo-second order kinetic and Langmuir isotherm models were that best fitted to the experimental data. The monolayer adsorption capacity was found to be 155.50mgg -1 . thermodynamic studies revealed that adsorption process is spontaneous, exothermic and occurs preferably via physisorption. The pineapple leaves are an efficient precursor for preparation of ACFs, which were successful applied as adsorbent material for removal of caffeine from the aqueous solutions. Copyright © 2017 Elsevier Inc. All rights reserved.

Formation and decomposition of ethane, propane, and carbon dioxide hydrates in silica gel mesopores under high pressure.

PubMed

Aladko, E Ya; Dyadin, Yu A; Fenelonov, V B; Larionov, E G; Manakov, A Yu; Mel'gunov, M S; Zhurko, F V

2006-10-05

The experimental data on decomposition temperatures for the gas hydrates of ethane, propane, and carbon dioxide dispersed in silica gel mesopores are reported. The studies were performed at pressures up to 1 GPa. It is shown that the experimental dependence of hydrate decomposition temperature on the size of pores that limit the size of hydrate particles can be described on the basis of the Gibbs-Thomson equation only if one takes into account changes in the shape coefficient that is present in the equation; in turn, the value of this coefficient depends on a method of mesopore size determination. A mechanism of hydrate formation in mesoporous medium is proposed. Experimental data providing evidence of the possibility of the formation of hydrate compounds in hydrophobic matrixes under high pressure are reported. Decomposition temperature of those hydrate compounds is higher than that for the bulk hydrates of the corresponding gases.

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

PubMed

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

2015-05-26

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

Hierarchical nanostructured hollow spherical carbon with mesoporous shell as a unique cathode catalyst support in proton exchange membrane fuel cell.

PubMed

Fang, Baizeng; Kim, Jung Ho; Kim, Minsik; Kim, Minwoo; Yu, Jong-Sung

2009-03-07

Hierarchical nanostructured spherical carbon with hollow macroporous core in combination with mesoporous shell has been explored to support Pt cathode catalyst with high metal loading in proton exchange membrane fuel cell (PEMFC). The hollow core-mesoporous shell carbon (HCMSC) has unique structural characteristics such as large specific surface area and mesoporous volume, ensuring uniform dispersion of the supported high loading (60 wt%) Pt nanoparticles with small particle size, and well-developed three-dimensionally interconnected hierarchical porosity network, facilitating fast mass transport. The HCMSC-supported Pt(60 wt%) cathode catalyst has demonstrated markedly enhanced catalytic activity toward oxygen reduction and greatly improved PEMFC polarization performance compared with carbon black Vulcan XC-72 (VC)-supported ones. Furthermore, the HCMSC-supported Pt(40 wt%) or Pt(60 wt%) outperforms the HCMSC-supported Pt(20 wt%) even at a low catalyst loading of 0.2 mg Pt cm(-2) in the cathode, which is completely different from the VC-supported Pt catalysts. The capability of supporting high loading Pt is supposed to accelerate the commercialization of PEMFC due to the anticipated significant reduction in the amount of catalyst support required, diffusion layer thickness and fabricating cost of the supported Pt catalyst electrode.

Nitrogen and Phosphorus Codoped Mesoporous Carbon Derived from Polypyrrole as Superior Metal-Free Electrocatalyst toward the Oxygen Reduction Reaction.

PubMed

Zhang, Zhengping; Sun, Junting; Dou, Meiling; Ji, Jing; Wang, Feng

2017-05-17

To replace high-cost platinum group metal (PGM) electrocatalysts for oxygen reduction reaction (ORR) that is the crucial cathode reaction in fuel cell technology and metal-air battery, the development of low-cost and high-efficiency non-PGM catalysts for ORR has attracted much attention during the past decades. As one of the promising candidates, N-doped carbon is highly desirable for its strong designability and outstanding catalytic activity and stability. In this work, a facile and rational strategy is demonstrated for preparation of N,P-codoped mesoporous carbon (N,P-MC) for ORR by the direct pyrolysis treatment of polypyrrole with phytic acid as P-dopant and polystyrene sphere as template. The resultant N,P-MC exhibits a mesoporous structure with the optimized ORR active sites originating from the N,P-codoping. Owing to these features, N,P-MC exhibits excellent ORR activity, remarkable electrochemical stability, and superior methanol tolerance, comparable or even better than that of commercial Pt/C catalyst. The origin of enhanced ORR performance can be attributed to both the increased active sites and the mesoporous structure, which is expected to guide the future preparation of more capable carbon-based electrocatalysts for oxygen reduction and other electrocatalytic application.

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

PubMed Central

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

2016-01-01

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

In-Situ-Activated N-Doped Mesoporous Carbon from a Protic Salt and Its Performance in Supercapacitors.

PubMed

Mendes, Tiago C; Xiao, Changlong; Zhou, Fengling; Li, Haitao; Knowles, Gregory P; Hilder, Matthias; Somers, Anthony; Howlett, Patrick C; MacFarlane, Douglas R

2016-12-28

Protic salts have been recently recognized to be an excellent carbon source to obtain highly ordered N-doped carbon without the need of tedious and time-consuming preparation steps that are usually involved in traditional polymer-based precursors. Herein, we report a direct co-pyrolysis of an easily synthesized protic salt (benzimidazolium triflate) with calcium and sodium citrate at 850 °C to obtain N-doped mesoporous carbons from a single calcination procedure. It was found that sodium citrate plays a role in the final carbon porosity and acts as an in situ activator. This results in a large surface area as high as 1738 m 2 /g with a homogeneous pore size distribution and a moderate nitrogen doping level of 3.1%. X-ray photoelectron spectroscopy (XPS) measurements revealed that graphitic and pyridinic groups are the main nitrogen species present in the material, and their content depends on the amount of sodium citrate used during pyrolysis. Transmission electron microscopy (TEM) investigation showed that sodium citrate assists the formation of graphitic domains and many carbon nanosheets were observed. When applied as supercapacitor electrodes, a specific capacitance of 111 F/g in organic electrolyte was obtained and an excellent capacitance retention of 85.9% was observed at a current density of 10 A/g. At an operating voltage of 3.0 V, the device provided a maximum energy density of 35 W h/kg and a maximum power density of 12 kW/kg.

Carboxyl-functionalized nanoparticles with magnetic core and mesopore carbon shell as adsorbents for the removal of heavy metal ions from aqueous solution.

PubMed

Wang, Hui; Yu, Yi-Fei; Chen, Qian-Wang; Cheng, Kai

2011-01-21

This communication demonstrates superparamagnetic nanosized particles with a magnetic core and a porous carbon shell (thickness of 11 nm), which can remove 97% of Pb(2+) ions from an acidic aqueous solution at a Pb(2+) ion concentration of 100 mg L(-1). It is suggested that a weak electrostatic force of attraction between the heavy metal ions and the nanoparticles and the heavy metal ions adsorption on the mesopore carbon shell contribute most to the superior removal property.

Preparation and Application of Electrodes in Capacitive Deionization (CDI): a State-of-Art Review.

PubMed

Jia, Baoping; Zhang, Wei

2016-12-01

As a promising desalination technology, capacitive deionization (CDI) have shown practicality and cost-effectiveness in brackish water treatment. Developing more efficient electrode materials is the key to improving salt removal performance. This work reviewed current progress on electrode fabrication in application of CDI. Fundamental principal (e.g. EDL theory and adsorption isotherms) and process factors (e.g. pore distribution, potential, salt type and concentration) of CDI performance were presented first. It was then followed by in-depth discussion and comparison on properties and fabrication technique of different electrodes, including carbon aerogel, activated carbon, carbon nanotubes, graphene and ordered mesoporous carbon. Finally, polyaniline as conductive polymer and its potential application as CDI electrode-enhancing materials were also discussed.

Nitrogen-doped hierarchical porous carbon with high surface area derived from graphene oxide/pitch oxide composite for supercapacitors.

PubMed

Ma, Yuan; Ma, Chang; Sheng, Jie; Zhang, Haixia; Wang, Ranran; Xie, Zhenyu; Shi, Jingli

2016-01-01

A nitrogen-doped hierarchical porous carbon has been prepared through one-step KOH activation of pitch oxide/graphene oxide composite. At a low weight ratio of KOH/composite (1:1), the as-prepared carbon possesses high specific surface area, rich nitrogen and oxygen, appropriate mesopore/micropore ratio and considerable small-sized mesopores. The addition of graphene oxide plays a key role in forming 4 nm mesopores. The sample PO-GO-16 presents the characteristics of large surface area (2196 m(2) g(-1)), high mesoporosity (47.6%), as well as rich nitrogen (1.52 at.%) and oxygen (6.9 at.%). As a result, PO-GO-16 electrode shows an outstanding capacitive behavior: high capacitance (296 F g(-1)) and ultrahigh-rate performance (192 F g(-1) at 10 A g(-1)) in 6 M KOH aqueous electrolyte. The balanced structure characteristic, low-cost and high performance, make the porous carbon a promising electrode material for supercapacitors. Copyright © 2015 Elsevier Inc. All rights reserved.

3D coral-like nitrogen-sulfur co-doped carbon-sulfur composite for high performance lithium-sulfur batteries

PubMed Central

Wu, Feng; Li, Jian; Tian, Yafen; Su, Yuefeng; Wang, Jing; Yang, Wen; Li, Ning; Chen, Shi; Bao, Liying

2015-01-01

3D coral-like, nitrogen and sulfur co-doped mesoporous carbon has been synthesized by a facile hydrothermal-nanocasting method to house sulfur for Li–S batteries. The primary doped species (pyridinic-N, pyrrolic-N, thiophenic-S and sulfonic-S) enable this carbon matrix to suppress the diffusion of polysulfides, while the interconnected mesoporous carbon network is favourable for rapid transport of both electrons and lithium ions. Based on the synergistic effect of N, S co-doping and the mesoporous conductive pathway, the as-fabricated C/S cathodes yield excellent cycling stability at a current rate of 4 C (1 C = 1675 mA g−1) with only 0.085% capacity decay per cycle for over 250 cycles and ultra-high rate capability (693 mAh g−1 at 10 C rate). These capabilities have rarely been reported before for Li-S batteries. PMID:26288961

Superior capacitive performance of hydrochar-based porous carbons in aqueous electrolytes.

PubMed

Fuertes, Antonio B; Sevilla, Marta

2015-03-01

Biomass-based highly porous carbons with excellent performances in aqueous electrolyte-based supercapacitors have been developed. The synthesis of these materials is based on the chemical activation of biomass-based hydrochar. The addition of melamine to the activation mixture leads to porous carbons with a porosity consisting of micropores/small mesopores. Furthermore, melamine promotes the introduction of nitrogen heteroatoms in the carbon framework, along with abundant oxygen functionalities, to improve the wettability. The materials produced in the presence or absence of melamine exhibit high specific capacitances in aqueous electrolytes (>270 F g(-1) in H2 SO4 and >190 F g(-1) in Li2SO4). Additionally, the mesopores present in the melamine-based micro-/mesoporous carbons notably improve the ion-transport kinetics, especially in Li2SO4. Furthermore, in Li2SO4, they remain stable up to a cell voltage of 1.6 V; thus exhibiting superior energy and power characteristics than those in H2 SO4. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

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

Villa, Alberto; Schiavoni, Marco; Fulvio, Pasquale F

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 andmore » 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« less

Excellent electrochemical performances of nanocast ordered mesoporous carbons based on tannin-related polyphenols as supercapacitor electrodes

NASA Astrophysics Data System (ADS)

Sanchez-Sanchez, A.; Izquierdo, Maria Teresa; Ghanbaja, Jaafar; Medjahdi, Ghouti; Mathieu, Sandrine; Celzard, Alain; Fierro, Vanessa

2017-03-01

Hierarchically porous, oxygen-doped ordered mesoporous carbons (OMCs) were synthesised and compared for the first time from different types of plant-derived polyphenols through a nanocasting route: phloroglucinol, gallic acid, catechin and Mimosa tannin. All are secondary metabolites naturally occurring in various plant species and are available at low cost at the industrial scale. The infiltration was carried out in one single step without using toxic solvents or long polymerisation-stabilisation times. When applied as electrode materials for supercapacitors in 1 M H2SO4 electrolyte, those OMCs led to specific capacitances up to 277 F g-1 at 0.5 mV s-1 and high rate capabilities as measured by cyclic voltammetry, good cycling stabilities up to 5000 cycles and maximum energy densities between 15 and 8 W h kg-1 under exceptionally high power outputs ranging from 200 W kg-1 to 22.1 kW kg-1, respectively, in the range of current density of 0.1-12 A g-1, as determined by galvanostatic charge - discharge. Moreover, electrochemical impedance spectroscopy tests evidenced that the gallic acid-derived electrode exhibited the highest electrical conductivity and the fastest frequency response, making it an excellent candidate for high-power commercial devices.

Thermo-sensitively and magnetically ordered mesoporous carbon nanospheres for targeted controlled drug release and hyperthermia application.

PubMed

Chen, Lin; Zhang, Huan; Zheng, Jing; Yu, Shiping; Du, Jinglei; Yang, Yongzhen; Liu, Xuguang

2018-03-01

A multifunctional nanoplatform based on thermo-sensitively and magnetically ordered mesoporous carbon nanospheres (TMOMCNs) is developed for effective targeted controlled release of doxorubicin hydrochloride (DOX) and hyperthermia in this work. The morphology, specific surface area, porosity, thermo-stability, thermo-sensitivity, as well as magnetism properties of TMOMCNs were verified by high resolution transmission electron microscopy, field emission scanning electron microscopy, thermo-gravimetric analysis, X-ray diffraction, Brunauer-Emmeltt-Teller surface area analysis, dynamic light scattering and vibrating sample magnetometry measurement. The results indicate that TMOMCNs have an average diameter of ~146nm with a lower critical solution temperature at around 39.5°C. They are superparamagnetic with a magnetization of 10.15emu/g at 20kOe. They generate heat when inductive magnetic field is applied to them and have a normalized specific absorption rate of 30.23W/g at 230kHz and 290Oe, showing good potential for hyperthermia. The DOX loading and release results illustrate that the loading capacity is 135.10mg/g and release performance could be regulated by changing pH and temperature. The good targeting, DOX loading and release and hyperthermia properties of TMOMCNs offer new probabilities for high effectiveness and low toxicity of cancer chemotherapy. Copyright © 2017 Elsevier B.V. All rights reserved.

Molecular simulation and experimental validation of resorcinol adsorption on Ordered Mesoporous Carbon (OMC).

PubMed

Ahmad, Zaki Uddin; Chao, Bing; Konggidinata, Mas Iwan; Lian, Qiyu; Zappi, Mark E; Gang, Daniel Dianchen

2018-04-27

Numerous research works have been devoted in the adsorption area using experimental approaches. All these approaches are based on trial and error process and extremely time consuming. Molecular simulation technique is a new tool that can be used to design and predict the performance of an adsorbent. This research proposed a simulation technique that can greatly reduce the time in designing the adsorbent. In this study, a new Rhombic ordered mesoporous carbon (OMC) model is proposed and constructed with various pore sizes and oxygen contents using Materials Visualizer Module to optimize the structure of OMC for resorcinol adsorption. The specific surface area, pore volume, small angle X-ray diffraction pattern, and resorcinol adsorption capacity were calculated by Forcite and Sorption module in Materials Studio Package. The simulation results were validated experimentally through synthesizing OMC with different pore sizes and oxygen contents prepared via hard template method employing SBA-15 silica scaffold. Boric acid was used as the pore expanding reagent to synthesize OMC with different pore sizes (from 4.6 to 11.3 nm) and varying oxygen contents (from 11.9% to 17.8%). Based on the simulation and experimental validation, the optimal pore size was found to be 6 nm for maximum adsorption of resorcinol. Copyright © 2018 Elsevier B.V. All rights reserved.

Template-mediated, Hierarchical Engineering of Ordered Mesoporous Films and Powders

NASA Astrophysics Data System (ADS)

Tian, Zheng

Hierarchical control over pore size, pore topology, and meso/mictrostructure as well as material morphology (e.g., powders, monoliths, thin films) is crucial for meeting diverse materials needs among applications spanning next generation catalysts, sensors, batteries, sorbents, etc. The overarching goal of this thesis is to establish fundamental mechanistic insight enabling new strategies for realizing such hierarchical textural control for carbon materials that is not currently achievable with sacrificial pore formation by 'one-pot' surfactant-based 'soft'-templating or multi-step inorganic 'hard-templating. While 'hard'-templating is often tacitly discounted based upon its perceived complexity, it offers potential for overcoming key 'soft'-templating challenges, including bolstering pore stability, accommodating a more versatile palette of replica precursors, realizing ordered/spanning porosity in the case of porous thin films, simplifying formation of bi-continuous pore topologies, and inducing microstructure control within porous replica materials. In this thesis, we establish strategies for hard-templating of hierarchically porous and structured carbon powders and tunable thin films by both multi-step hard-templating and a new 'one-pot' template-replica precursor co-assembly process. We first develop a nominal hard-templating technique to successfully prepare three-dimensionally ordered mesoporous (3DOm) and 3DOm-supported microporous carbon thin films by exploiting our ability to synthesize and assemble size-tunable silica nanoparticles into scalable, colloidal crystalline thin film templates of tunable mono- to multi-layer thickness. This robust thin film template accommodates liquid and/or vapor-phase infiltration, polymerization, and pyrolysis of various carbon sources without pore contraction and/or collapse upon template sacrifice. The result is robust, flexible 3DOm or 3DOm-supported ultra-thin microporous films that can be transferred by stamp techniques to various substrates for low-cost counter-electrodes in dye-sensitized solar cells, as we demonstrate, or as potential high-flux membranes for molecular separations. Inspired by 'one-pot' 'soft'-templating approaches, wherein the pore forming agent and replica precursor are co-assembled, we establish how 'hard'-templating can be carried out in an analogous fashion. Namely, we show how pre-formed silica nanoparticles can be co-assembled from aqueous solutions with a carbon source (glucose), leading to elucidation of a pseudo-phase behavior in which we identify an operating window for synthesis of hierarchically bi-continuous carbon films. Systematic study of the association of carbon precursors with the silica particles in combination with transient coating experiments reveals mechanistic insight into how silica-adsorbed carbon precursor modulates particle assembly and ultimately controls template particle d-spacing. We uncover a critical d-spacing defining the boundary between ordered and disordered mesoporosity within the resulting films. We ultimately extend this thin-film mechanistic insight to realize 'one'-pot, bi-continuous 3DOm carbon powders. Through a combination of X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and high-resolution transmission electron microscopy (HR-TEM), we elucidate novel synthesis-structure relations for template-mediated microstructuring of the 3DOm replica carbons. Attractive properties of the resulting bi-continuous porous carbons for applications, for example, as novel electrodes, include high surface areas, large mesopore volumes, and tunable graphitic content (i.e. >50%) and character. We specifically demonstrate their performance, in thin film form, as counter-electrodes in dye-sensitized solar cells. We also demonstrate how they can be exploited in powder form as high-performance supercapacitor electrodes exhibiting attractive retention and absolute capacitance. We conclude the thesis by demonstrating the versatility of both the thin-film and powder templating processes developed herein, for realizing ordered binary colloidal crystal templates and their bi-modal porous carbon replica films, expanding compositional diversity of the 'one-pot' thin film process beyond carbons to include an example of 3DOm ZrO2 films, and employing the hard-templating process as a strategy for realizing 3DOm carbon-supported nanocarbides.

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

PubMed Central

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

2012-01-01

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

Electrochemical performance of microporous and mesoporous activated carbons in neat and diluted 1-ethyl-3-methylimidazolium tetrafluoroborate

NASA Astrophysics Data System (ADS)

Kumagai, Seiji; Hatomi, Masaki; Tashima, Daisuke

2017-03-01

1-Ethyl-3-methylimidazolium tetrafluoroborate (EMIm·BF4), neat and diluted with propylene carbonate to 1 mol L-1, have been employed as electrolytes of electrical double-layer capacitors (EDLCs). The effects of microporosity and mesoporosity in activated carbon (AC) electrodes on the capacitive and resistive performances upon the use of neat and diluted EMIm·BF4 have been explored. In addition to cyclic voltammetry and galvanostatic charge-discharge tests, electrochemical impedance spectroscopy has been performed employing Kang's equivalent circuit model consisting of three resistances, three constant phase elements, and one bounded Warburg impedance. The overall impedance of the EDLC cell was separated into components of intrinsic resistance, bulk electrolyte, diffusion layer, and Helmholtz layer. The specific capacitance and the equivalent series resistance (ESR) of mesoporous AC were found to be highly dependent on the rate of ionic transfer. Lower cell voltage was identified as being responsible for lower specific capacitance and larger ESR of mesoporous AC, which was similarly seen in the neat and diluted EMIm·BF4, and could be alleviated by increasing the cell voltage. The inferior rate performance and the cell-voltage-dependent performance of mesoporous AC, which were more distinctly observed in the neat EMIm·BF4, could be attributed to the lower mobility of EMIm+ and BF4- in mesopores.

A floating macro/mesoporous crystalline anatase TiO2 ceramic with enhanced photocatalytic performance for recalcitrant wastewater degradation.

PubMed

Xing, Zipeng; Zhou, Wei; Du, Fan; Qu, Yang; Tian, Guohui; Pan, Kai; Tian, Chungui; Fu, Honggang

2014-01-14

A macro/mesoporous anatase TiO2 ceramic floating photocatalyst has been successfully synthesized using highly thermally stable mesoporous TiO2 powder as a precursor, followed by a camphene-based freeze-casting process and high-temperature calcinations. The ceramics are characterized in detail by X-ray diffraction, Raman spectra, scanning electron microscopy, transmission electron microscopy and N2 adsorption-desorption isotherms. The results indicate that the TiO2 ceramics present hierarchical macro/mesoporous structures, which maintain high porosity and high compressive strength at the optimal sintering temperature of 800 °C. The ordered mesoporous TiO2 network still possesses high thermal stability and inhibits the anatase-to-rutile phase transformation during calcinations. The obtained ceramics exhibit good adsorptive and photocatalytic activity for the degradation of octane and rhodamine B, and the total organic carbon removal ratio is up to 98.8% and 98.6% after photodegradation for 3 h, respectively. The roles of active species in the photocatalytic process are compared using different types of active species scavengers, and the degradation mechanism is also proposed. Furthermore, the ceramics are recyclable, and no clear changes are observed after ten cycles. In addition, the ceramics are also active in the photodegradation of phenol, thiobencarb, and atrazine. Therefore, these novel floating photocatalysts will have wide applications, including the removal of floating organic pollutants from the wastewater surfaces or the removal of soluble organic pollutants from wastewater.

Tailored Mesoporous Silicas: From Confinement Effects to Catalysis

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

Buchanan III, A C; Kidder, Michelle

2010-01-01

Ordered mesoporous silicas continue to find widespread use as supports for diverse applications such as catalysis, separations, and sensors. They provide a versatile platform for these studies because of their high surface area and the ability to control pore size, topology, and surface properties over wide ranges. Furthermore, there is a diverse array of synthetic methodologies for tailoring the pore surface with organic, organometallic, and inorganic functional groups. In this paper, we will discuss two examples of tailored mesoporous silicas and the resultant impact on chemical reactivity. First, we explore the impact of pore confinement on the thermochemical reactivity ofmore » phenethyl phenyl ether (PhCH2CH2OPh, PPE), which is a model of the dominant {beta}-aryl ether linkage present in lignin derived from woody biomass. The influence of PPE surface immobilization, grafting density, silica pore diameter, and presence of a second surface-grafted inert 'spacer' molecule on the product selectivity has been examined. We will show that the product selectivity can be substantially altered compared with the inherent gas-phase selectivity. Second, we have recently initiated an investigation of mesoporous silica supported, heterobimetallic oxide materials for photocatalytic conversion of carbon dioxide. Through surface organometallic chemistry, isolated M-O-M species can be generated on mesoporous silicas that, upon irradiation, form metal to metal charge transfer bands capable of converting CO{sub 2} into CO. Initial results from studies of Ti(IV)-O-Sn(II) on SBA-15 will be presented.« less

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

PubMed

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

2016-02-08

The lack of safe, efficient, and economical hydrogen storage technologies is a hindrance to the realization of the hydrogen economy. Reported herein is a reversible formate-based carbon-neutral hydrogen storage system that is established over a novel catalyst comprising palladium nanoparticles supported on nitrogen-doped mesoporous carbon. The support was fabricated by a hard template method and nitridated under a flow of ammonia. Detailed analyses demonstrate that this bicarbonate/formate redox equilibrium is promoted by the cooperative role of the doped nitrogen functionalities and the well-dispersed, electron-enriched palladium nanoparticles. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis of rambutan-like MoS2/mesoporous carbon spheres nanocomposites with excellent performance for supercapacitors

NASA Astrophysics Data System (ADS)

Zhang, Shouchuan; Hu, Ruirui; Dai, Peng; Yu, Xinxin; Ding, Zongling; Wu, Mingzai; Li, Guang; Ma, Yongqing; Tu, Chuanjun

2017-02-01

A novel rambutan-like composite of MoS2/mesoporous carbon spheres were synthesized by a simple two-step hydrothermal and post-annealing approach via using glucose as C source and Na2MoO4·2H2O and thiourea as Mo and S sources. It is found that the morphology and electrochemical properties can be effectively controlled by the change of the weight ratio of coated MoS2 sheets to carbon spheres. When used as electrode material for supercapacitor, the hybrid MoS2/carbon spheres show a high specific capacity of 411 F/g at a current density of 1 A/g and 272 F/g at a high discharge current density of 10 A/g. The annealing treatment at 700 °C transformed the core carbon spheres into mesoporous ones, which served as the conduction network and favor the enhancement of the specific capacitance. In addition, the strain released during the charge/discharge process can be accommodated and the structural integrity can be kept, improving the cycling life. After 1000 cycles, the capacitance retention of the hybrid MoS2/carbon spheres is 93.2%.

Electrolyte Engineering: Optimizing High-Rate Double-Layer Capacitances of Micropore- and Mesopore-Rich Activated Carbon.

PubMed

Chen, Ting-Hao; Yang, Cheng-Hsien; Su, Ching-Yuan; Lee, Tai-Chou; Dong, Quan-Feng; Chang, Jeng-Kuei

2017-09-22

Various types of electrolyte cations as well as binary cations are used to optimize the capacitive performance of activated carbon (AC) with different pore structures. The high-rate capability of micropore-rich AC, governed by the mobility of desolvated cations, can outperform that of mesopore-rich AC, which essentially depends on the electrolyte conductivity. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

PubMed

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

2016-11-01

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

Hollow mesoporous carbon as a near-infrared absorbing carrier compared with mesoporous carbon nanoparticles for chemo-photothermal therapy.

PubMed

Li, Xian; Yan, Yue; Lin, Yuanzhe; Jiao, Jian; Wang, Da; Di, Donghua; Zhang, Ying; Jiang, Tongying; Zhao, Qinfu; Wang, Siling

2017-05-15

In this study, hollow mesoporous carbon nanoparticles (HMCN) and mesoporous carbon nanoparticles (MCN) were used as near-infrared region (NIR) nanomaterials and drug nanocarriers were prepared using different methods. A comparison between HMCN and MCN was performed with regard to the NIR-induced photothermal effect and drug loading efficiency. The results of NIR-induced photothermal effect test demonstrated that HMCN-COOH had a better photothermal conversion efficacy than MCN-COOH. Given the prominent photothermal effect of HMCN-COOH in vitro, the chemotherapeutic drug DOX was chosen as a model drug to further evaluate the drug loading efficiencies and NIR-triggered drug release behaviors of the nanocarriers. The drug loading efficiency of DOX/HMCN-COOH was found to be up to 76.9%, which was higher than that of DOX/MCN-COOH. In addition, the use of an 808nm NIR laser markedly increased the release of DOX from both carbon carriers in pH 5.0 PBS and pH 7.4 PBS. Cellular photothermal tests involving A549 cells demonstrated that HMCN-COOH had a much higher photothermal efficacy than MCN-COOH. Cell viability experiments and flow cytometry were performed to evaluate the therapeutic effect of DOX/HMCN-COOH and the results obtained demonstrated that DOX/HMCN-COOH had a synergistic therapeutic effect in cancer treatment involving a combination of chemotherapy and photothermal therapy. Copyright © 2017 Elsevier Inc. All rights reserved.

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

NASA Astrophysics Data System (ADS)

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

2015-12-01

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

Enabling high-rate electrochemical flow capacitors based on mesoporous carbon microspheres suspension electrodes

NASA Astrophysics Data System (ADS)

Tian, Meng; Sun, Yueqing; Zhang, Chuanfang (John); Wang, Jitong; Qiao, Wenming; Ling, Licheng; Long, Donghui

2017-10-01

Electrochemical flow capacitor (EFC) is a promising technology for grid energy storage, which combines the fast charging/discharging capability of supercapacitors with the scalable energy capacity of flow batteries. In this study, we report a high-power-density EFC using mesoporous carbon microspheres (MCMs) as suspension electrodes. By using a simple yet effective spray-drying technique, monodispersed MCMs with average particle size of 5 μm, high BET surface area of 1150-1267 m2 g-1, large pore volume of 2-4 cm3 g-1 and controllable mesopore size of 7-30 nm have been successfully prepared. The resultant MCMs suspension electrode shows excellent stability and considerable high capacitance of 100 F g-1 and good cycling ability (86% of initial capacitance after 10000 cycles). Specially, the suspension electrode exhibits excellent rate performance with 75% capacitance retention from 2 to 100 mV s-1, significantly higher than that of microporous carbon electrodes (20∼30%), due to the developed mesoporous channels facilitating for rapid ion diffusion. In addition, the electrochemical responses on both negative and positive suspension electrodes are studied, based on which an optimal capacitance matching between them is suggested for large-scale EFC unit.

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

PubMed

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

2010-02-16

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

Multicomponent Nanomaterials with Complex Networked Architectures from Orthogonal Degradation and Binary Metal Backfilling in ABC Triblock Terpolymers

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

Cowman, Christina D.; Padgett, Elliot; Tan, Kwan Wee

2015-05-13

Selective degradation of block copolymer templates and backfilling the open mesopores is an effective strategy for the synthesis of nanostructured hybrid and inorganic materials. Incorporation of more than one type of inorganic material in orthogonal ways enables the synthesis of multicomponent nanomaterials with complex yet well-controlled architectures; however, developments in this field have been limited by the availability of appropriate orthogonally degradable block copolymers for use as templates. We report the synthesis and self-assembly into cocontinuous network structures of polyisoprene-block-polystyrene-block-poly(propylene carbonate) where the polyisoprene and poly(propylene carbonate) blocks can be orthogonally removed from the polymer film. Through sequential block etchingmore » and backfilling the resulting mesopores with different metals, we demonstrate first steps toward the preparation of three-component polymer–inorganic hybrid materials with two distinct metal networks. Multiblock copolymers in which two blocks can be degraded and backfilled independently of each other, without interference from the other, may be used in a wide range of applications requiring periodically ordered complex multicomponent nanoarchitectures.« less

Multicomponent nanomaterials with complex networked architectures from orthogonal degradation and binary metal backfilling in ABC triblock terpolymers

DOE PAGES

Cowman, Christina D.; Padgett, Elliot; Tan, Kwan Wee; ...

2015-04-02

Selective degradation of block copolymer templates and backfilling the open mesopores is an effective strategy for the synthesis of nanostructured hybrid and inorganic materials. Incorporation of more than one type of inorganic material in orthogonal ways enables the synthesis of multicomponent nanomaterials with complex yet well-controlled architectures; however, developments in this field have been limited by the availability of appropriate orthogonally degradable block copolymers for use as templates. We report the synthesis and self-assembly into cocontinuous network structures of polyisoprene-block-polystyrene-block-poly(propylene carbonate) where the polyisoprene and poly(propylene carbonate) blocks can be orthogonally removed from the polymer film. Through sequential block etchingmore » and backfilling the resulting mesopores with different metals, we demonstrate first steps toward the preparation of three-component polymer–inorganic hybrid materials with two distinct metal networks. Lastly, multiblock copolymers in which two blocks can be degraded and backfilled independently of each other, without interference from the other, may be used in a wide range of applications requiring periodically ordered complex multicomponent nanoarchitectures.« less

Facile synthesis of mesoporous lithium titanate spheres for high rate lithium-ion batteries

NASA Astrophysics Data System (ADS)

Lin, Yu-Sheng; Duh, Jenq-Gong

Lithium titanate is synthesized from titanium isopropoxide and lithium acetate solution under hydrothermal environment and calcinations. Introducing acidized carbon black during synthesis can produce mesoporous Li 4Ti 5O 12. The crystalline structure and morphological observation of the as-synthesized mesoporous Li 4Ti 5O 12 are characterized by X-ray diffraction (XRD) and scanning electron microscopy, respectively. The mesoporous structure can be directly observed through BEI images of the cross-section sample. Besides, N 2 adsorption/desorption isotherm also displays a hysteresis loop, implying the beneficial evidence of mesoporous structure. The pore size distribution of mesoporous lithium titanate evaluated by BJH model is narrow, and the average size of voids is around 4 nm. It is demonstrated that the electrochemical performance is significantly improved by the mesoporous structure. The mesoporous lithium titanate exhibits a stable capacity of 140 mAhg -1 at 0.5 C. Besides, the reversible capacity at 30 C remains over half of that at 0.5 C. The superior C-rate performance is associated with the mesoporous structure, facilitating lithium transportation ability during cycling.

Insight into the Capacity Fading Mechanism of Amorphous Se 2 S 5 Confined in Micro/Mesoporous Carbon Matrix in Ether-Based Electrolytes

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

Xu, Gui-Liang; Ma, Tianyuan; Sun, Cheng-Jun

2016-04-13

In contrast to the stable cycle performance of space confined Se-based cathodes for lithium batteries in carbonate-based electrolytes, their common capacity fading in ether-based electrolytes has been paid less attention and not yet well-addressed so far. In this work, the lithiation/delithiation of amorphous Se2S5 confined in micro/mesoporous carbon (Se2S5/MPC) cathode was investigated by in situ X-ray near edge absorption spectroscopy (XANES) and theoretical calculations. The Se2S5/MPC composite was synthesized by a modified vaporization-condensation method to ensure a good encapsulation of Se2S5 into the pores of MPC host. In situ XANES results illustrated that the lithiation/delithiation reversibility of Se component wasmore » gradually decreased in ether-based electrolytes, leading to an aggravated formation of long-chain polyselenides during cycling and further capacity decay. Moreover, ab initio calculations revealed that the binding energy of polyselenides (Li2Sen) with carbon host is in an order of Li2Se6 > Li2Se4 > Li2Se. The insights into the failure mechanism of Se-based cathode gain in this work are expected to serve as a guide for future design on high performance Se-based cathodes.« less

Adsorption of ciprofloxacin, bisphenol and 2-chlorophenol on electrospun carbon nanofibers: in comparison with powder activated carbon.

PubMed

Li, Xiaona; Chen, Shuo; Fan, Xinfei; Quan, Xie; Tan, Feng; Zhang, Yaobin; Gao, Jinsuo

2015-06-01

Carbon nanofibers (CNFs) were prepared by electrospun polyacrylonitrile (PAN) polymer solutions followed by thermal treatment. For the first time, the influence of stabilization procedure on the structure properties of CNFs was explored to improve the adsorption capacity of CNFs towards the environmental pollutants from aqueous solution. The adsorption of three organic chemicals including ciprofloxacin (CIP), bisphenol (BPA) and 2-chlorophenol (2-CP) on electrospun CNFs with high surface area of 2326m(2)/g and micro/mesoporous structure characteristics were investigated. The adsorption affinities were compared with that of the commercial powder activated carbon (PAC). The adsorption kinetics and isotherms showed that the maximum adsorption capacities (qm) of CNFs towards the three pollutants are sequenced in the order of CIP>BPA>2-CP, which are 2.6-fold (CIP), 1.6-fold (BPA) and 1.1-fold (2-CP) increase respectively in comparison with that of PAC adsorption. It was assumed that the micro/mesoporous structure of CNFs, molecular size of the pollutants and the π electron interaction play important roles on the high adsorption capacity exhibited by CNFs. In addition, electrostatic interaction and hydrophobic interaction also contribute to the adsorption of CNFs. This study demonstrates that the electrospun CNFs are promising adsorbents for the removal of pollutants from aqueous solutions. Copyright © 2015 Elsevier Inc. All rights reserved.

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

PubMed

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

2014-10-08

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

A fluorescent sensor for selective detection of cyanide using mesoporous graphitic carbon(IV) nitride.

PubMed

Lee, Eun Zoo; Lee, Sun Uk; Heo, Nam-Su; Stucky, Galen D; Jun, Young-Si; Hong, Won Hi

2012-04-25

A turn-on fluorescence sensor, Cu(2+)-c-mpg-C(3)N(4), was developed for detection of CN(-) in aqueous solution by simply mixing cubic mesoporous graphitic carbon nitride (c-mpg-C(3)N(4)) and aqueous solution of Cu(NO(3))(2). The highly sensitive detection of CN(-) with a detection limit of 80 nM is not only possible in aqueous solution but also in human blood serum.

3D hybrid-porous carbon derived from carbonization of metal organic frameworks for high performance supercapacitors

NASA Astrophysics Data System (ADS)

Bao, Weizhai; Mondal, Anjon Kumar; Xu, Jing; Wang, Chengyin; Su, Dawei; Wang, Guoxiu

2016-09-01

We report a rational design and synthesis of 3D hybrid-porous carbon with a hierarchical pore architecture for high performance supercapacitors. It contains micropores (<2 nm diameter) and mesopores (2-4 nm), derived from carbonization of unique porous metal organic frameworks (MOFs). Owning to the synergistic effect of micropores and mesopores, the hybrid-porous carbon has exceptionally high ion-accessible surface area and low ion diffusion resistance, which is desired for supercapacitor applications. When applied as electrode materials in supercapacitors, 3D hybrid-porous carbon demonstrates a specific capacitance of 332 F g-1 at a constant charge/discharge current of 500 mA g-1. The supercapacitors can endure more than 10,000 cycles without degradation of capacitance.

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

NASA Astrophysics Data System (ADS)

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

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

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

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

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

2013-06-01

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

Spatially and size selective synthesis of Fe-based nanoparticles on ordered mesoporous supports as highly active and stable catalysts for ammonia decomposition.

PubMed

Lu, An-Hui; Nitz, Joerg-Joachim; Comotti, Massimiliano; Weidenthaler, Claudia; Schlichte, Klaus; Lehmann, Christian W; Terasaki, Osamu; Schüth, Ferdi

2010-10-13

Uniform and highly dispersed γ-Fe(2)O(3) nanoparticles with a diameter of ∼6 nm supported on CMK-5 carbons and C/SBA-15 composites were prepared via simple impregnation and thermal treatment. The nanostructures of these materials were characterized by XRD, Mössbauer spectroscopy, XPS, SEM, TEM, and nitrogen sorption. Due to the confinement effect of the mesoporous ordered matrices, γ-Fe(2)O(3) nanoparticles were fully immobilized within the channels of the supports. Even at high Fe-loadings (up to about 12 wt %) on CMK-5 carbon no iron species were detected on the external surface of the carbon support by XPS analysis and electron microscopy. Fe(2)O(3)/CMK-5 showed the highest ammonia decomposition activity of all previously described Fe-based catalysts in this reaction. Complete ammonia decomposition was achieved at 700 °C and space velocities as high as 60,000 cm(3) g(cat)(-1) h(-1). At a space velocity of 7500 cm(3) g(cat)(-1) h(-1), complete ammonia conversion was maintained at 600 °C for 20 h. After the reaction, the immobilized γ-Fe(2)O(3) nanoparticles were found to be converted to much smaller nanoparticles (γ-Fe(2)O(3) and a small fraction of nitride), which were still embedded within the carbon matrix. The Fe(2)O(3)/CMK-5 catalyst is much more active than the benchmark NiO/Al(2)O(3) catalyst at high space velocity, due to its highly developed mesoporosity. γ-Fe(2)O(3) nanoparticles supported on carbon-silica composites are structurally much more stable over extended periods of time but less active than those supported on carbon. TEM observation reveals that iron-based nanoparticles penetrate through the carbon layer and then are anchored on the silica walls, thus preventing them from moving and sintering. In this way, the stability of the carbon-silica catalyst is improved. Comparison with the silica supported iron oxide catalyst reveals that the presence of a thin layer of carbon is essential for increased catalytic activity.

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

PubMed

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

2013-01-01

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

Quasielastic neutron scattering study of water confined in carbon nanopores

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

Mavila Chathoth, Suresh; Mamontov, Eugene; Kolesnikov, Alexander I

2011-01-01

Microscopic dynamics of water confined in nanometer and sub-nanometer pores of carbide-derived carbon (CDC) were investigated using quasielastic neutron scattering (QENS). The temperature dependence of the average relaxation time, {tau}, exhibits super-Arrhenius behavior that could be described by Vogel-Fulcher-Tammann (VFT) law in the range from 250 K to 190 K; below this temperature, {tau} follows Arrhenius temperature dependence. The temperature of the dynamic crossover between the two regimes in water confined in the CDC pores is similar to that observed for water in hydrophobic confinement of the larger size, such as 14 {angstrom} ordered mesoporous carbon (CMK) and 16 {angstrom}more » double-wall carbon nanotubes. Thus, the dynamical behavior of water remains qualitatively unchanged even in the very small hydrophobic pores.« less

Hierarchical meso/macro-porous carbon fabricated from dual MgO templates for direct electron transfer enzymatic electrodes.

PubMed

Funabashi, Hiroto; Takeuchi, Satoshi; Tsujimura, Seiya

2017-03-23

We designed a three-dimensional (3D) hierarchical pore structure to improve the current production efficiency and stability of direct electron transfer-type biocathodes. The 3D hierarchical electrode structure was fabricated using a MgO-templated porous carbon framework produced from two MgO templates with sizes of 40 and 150 nm. The results revealed that the optimal pore composition for a bilirubin oxidase-catalysed oxygen reduction cathode was a mixture of 33% macropores and 67% mesopores (MgOC 33 ). The macropores improve mass transfer inside the carbon material, and the mesopores improve the electron transfer efficiency of the enzyme by surrounding the enzyme with carbon.

Hierarchical meso/macro-porous carbon fabricated from dual MgO templates for direct electron transfer enzymatic electrodes

NASA Astrophysics Data System (ADS)

Funabashi, Hiroto; Takeuchi, Satoshi; Tsujimura, Seiya

2017-03-01

We designed a three-dimensional (3D) hierarchical pore structure to improve the current production efficiency and stability of direct electron transfer-type biocathodes. The 3D hierarchical electrode structure was fabricated using a MgO-templated porous carbon framework produced from two MgO templates with sizes of 40 and 150 nm. The results revealed that the optimal pore composition for a bilirubin oxidase-catalysed oxygen reduction cathode was a mixture of 33% macropores and 67% mesopores (MgOC33). The macropores improve mass transfer inside the carbon material, and the mesopores improve the electron transfer efficiency of the enzyme by surrounding the enzyme with carbon.

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

PubMed

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

2018-04-16

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

Cu2S-Cu-TiO2 mesoporous carbon composites for the degradation of high concentration of methyl orange under visible light

NASA Astrophysics Data System (ADS)

Zhang, Liang; Zhao, Yuan; Zhong, Lvling; Wang, Yang; Chai, Shouning; Yang, Tao; Han, Xuanli

2017-11-01

A Schiff base compound was used to prepare a Cu2S-Cu-TiO2 mesoporous carbon composite photocatalyst (Cu2S-Cu-TiO2/MC) by a simple precipitation-carbonization method with a carbonization temperature of 750 °C. X-ray diffraction and x-ray photoelectron spectroscopy studies show that Cu2S, Cu, and TiO2 exist in Cu2S-Cu-TiO2/MC in the form of nanometer-sized particles. Scanning electron microscope and transmission electron microscope images show that the composites form a spherical carbon structure inlaid with Cu2S and Cu and coated TiO2. The Brunauer-Emmett-Teller test shows that the material has a large specific surface area (76.14 m2/g) and mesoporous structure. UV-vis diffuse reflection spectroscopy and photoluminescence spectroscopy indicate that the recombination of photo-generated electrons and holes in the samples were inhibited. The composites show good degradation performance in a high concentration (300 mg/L) of methyl orange (MO) solution under visible light. The composites exhibit great potential in the treatment of dyes for wastewater treatment.

Hierarchical porous silicon carbide with controlled micropores and mesopores for electric double layer capacitors

NASA Astrophysics Data System (ADS)

Kim, Myeongjin; Oh, Ilgeun; Kim, Jooheon

2015-05-01

Three-dimensional hierarchical micro and mesoporous silicon carbide spheres (MMPSiC) are prepared by the template method and carbonization reaction via the aerosol spray drying method. The mesopores are generated by the self-assembly of the structure-directing agents, whereas the micropores are derived from the partial evaporation of Si atoms during carbonization. To investigate the effect of mesopore size on electrochemical performance, three types of MMPSiC with different mesopore size were fabricated by using three different structure directing agents (cetyltriethylammonium bromide (CTAB), Polyethylene glycol hexadecyl ether (Brij56), and Poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) (P123)). The MMPSiC electrode prepared with Brij56 exhibits the highest charge storage capacity with a specific capacitance of 253.7 F g-1 at a scan rate of 5 mV s-1 and 87.9% rate performance from 5 to 500 mV s-1 in 1 M Na2SO4 aqueous electrolyte. The outstanding electrochemical performance might be because of the ideal mesopore size, which effectively reduces the resistant pathways for ion diffusion in the pores and provides a large accessible surface area for ion transport/charge storage. These encouraging results demonstrate that the MMPSiC prepared with Brij56 is a promising candidate for high performance electrode materials for supercapacitors.

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

PubMed

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

2015-04-14

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

Synergistic effects of graphene quantum dot sensitization and nitrogen doping of ordered mesoporous TiO2 thin films for water splitting photocatalysis(Conference Presentation)

NASA Astrophysics Data System (ADS)

Islam, Syed Z.; Wanninayake, Namal; Reed, Allen D.; Kim, Doo-Young; Rankin, Stephen E.

2016-10-01

The optical and electronic properties of TiO2 thin films provide tremendous opportunities in several applications including photocatalysis, photovoltaics and photoconductors for energy production. Despite many attractive features of TiO2, critical challenges include the innate inability of TiO2 to absorb visible light and the fast recombination of photoexcited charge carriers. In this study, we prepared ordered mesoporous TiO2 films co-modified by graphene quantum dot sensitization and nitrogen doping (GQD-N-TiO2) for hydrogen production from photoelectrochemical water splitting under visible light irradiation. First, cubic ordered mesoporous TiO2 films were prepared by a surfactant templated sol-gel method. Then, TiO2 films were treated with N2/Ar plasma for the incorporation of substitutional N atoms into the lattice of TiO2. GQDs were prepared by chemically oxidizing carbon nano-onions. The immobilization of GQDs was accomplished by reacting carboxyl groups of GQDs with amine groups of N-TiO2 developed by the prior immobilization of (3-aminopropyl)triethoxysilane (APTES). Successful immobilization of GQDs onto N-TiO2 was probed by UV-Vis, FT-IR, and scanning electron microscopy. Further, zeta potential and contact angle measurements showed enhanced surface charge and hydrophilicity, confirming the successful immobilization of GQDs. The GQD-N-TiO2, N-TiO2 and GQD-TiO2 films showed 400 times, 130 times and 8 times photocurrent enhancement, respectively, compared to TiO2 films for water splitting with a halogen bulb light source. This outstanding enhancement is attributed to the high surface area of mesoporous films and synergistic effects of nitrogen doping and GQD sensitization resulting in enhanced visible light absorption, efficient charge separation and transport.

High-surface-area mesoporous TiO2 microspheres via one-step nanoparticle self-assembly for enhanced lithium-ion storage

NASA Astrophysics Data System (ADS)

Wang, Hsin-Yi; Chen, Jiazang; Hy, Sunny; Yu, Linghui; Xu, Zhichuan; Liu, Bin

2014-11-01

Mesoporous TiO2 microspheres assembled from TiO2 nanoparticles with specific surface areas as high as 150 m2 g-1 were synthesized via a facile one-step solvothermal reaction of titanium isopropoxide and anhydrous acetone. Aldol condensation of acetone gradually releases structural H2O, which hydrolyzes and condenses titanium isopropoxide, forming TiO2 nanocrystals. Simultaneous growth and aggregation of TiO2 nanocrystals leads to the formation of high-surface-area TiO2 microspheres under solvothermal conditions. After a low-temperature post-synthesis calcination, carbonate could be incorporated into TiO2 as a dopant with the carbon source coming from the organic byproducts during the synthesis. Carbonate doping modifies the electronic structure of TiO2 (e.g., Fermi level, Ef), and thus influences its electrochemical properties. Solid electrolyte interface (SEI) formation, which is not common for titania, could be initiated in carbonate-doped TiO2 due to elevated Ef. After removing carbonate dopants by high-temperature calcination, the mesoporous TiO2 microspheres showed much improved performance in lithium insertion and stability at various current rates, attributed to a synergistic effect of high surface area, large pore size and good anatase crystallinity.Mesoporous TiO2 microspheres assembled from TiO2 nanoparticles with specific surface areas as high as 150 m2 g-1 were synthesized via a facile one-step solvothermal reaction of titanium isopropoxide and anhydrous acetone. Aldol condensation of acetone gradually releases structural H2O, which hydrolyzes and condenses titanium isopropoxide, forming TiO2 nanocrystals. Simultaneous growth and aggregation of TiO2 nanocrystals leads to the formation of high-surface-area TiO2 microspheres under solvothermal conditions. After a low-temperature post-synthesis calcination, carbonate could be incorporated into TiO2 as a dopant with the carbon source coming from the organic byproducts during the synthesis. Carbonate doping modifies the electronic structure of TiO2 (e.g., Fermi level, Ef), and thus influences its electrochemical properties. Solid electrolyte interface (SEI) formation, which is not common for titania, could be initiated in carbonate-doped TiO2 due to elevated Ef. After removing carbonate dopants by high-temperature calcination, the mesoporous TiO2 microspheres showed much improved performance in lithium insertion and stability at various current rates, attributed to a synergistic effect of high surface area, large pore size and good anatase crystallinity. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr04729j

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

PubMed

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

2015-01-21

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

The role of mass transport pathway in wormholelike mesoporous carbon for supercapacitors.

PubMed

Liang, Yeru; Liang, Fengxue; Li, Zhenghui; Wu, Dingcai; Yan, Fangyu; Li, Siyu; Fu, Ruowen

2010-09-28

In the present paper, we demonstrate the importance of the role of a mass transport pathway (MTP) in wormholelike mesoporous carbon (WMC) through studying the ion diffusion behaviors within two different wormholelike mesopore networks with and without MTP. Our results reveal that the introduction of MTP is very helpful in improving ion diffusion properties. The as-prepared WMC with a MTP of ca. 9.7 nm exhibits notably better electric double layer performance as compared to the conventional WMC without a MTP. For example, even at the quick sweep rate of 50 mV s(-1), the surface specific capacitance of the former is 21.6 microF cm(-2), which is almost 4 times as high as that of the latter (5.5 microF cm(-2)).

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

PubMed

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

2016-01-01

A novel label-free impedimetric sensing system based on DNAzyme and ordered mesoporous carbon-gold nanoparticle (OMC-GNPs) for the determination of Pb(2+) concentration was developed in the present study. Firstly, gold nanoparticles deposited on the modified electrode surface were employed as a platform for the immobilization of thiolated probe DNA, and then hybridized with DNAzyme catalytic beacons. Subsequently, in the presence of Pb(2+), the DNAzyme could be activated to cleave the substrate strand into two DNA fragments, which causes differences in the electrical properties of the film. Randles equivalent circuit was employed to evaluate the electrochemical impedance spectroscopy (EIS) result. The charge transfer resistance (R(CT)) value for the [Fe(CN)6](3-/4-) redox indicator was remarkably decline after hybridization with Pb(2+). The difference in RCT values before and after hybridization with Pb(2+) showed a linear relation with the concentration of the Pb(2+) in a range of 5×10(-10)-5×10(-5) M, with a detection limit of 2×10(-10) M (S/N=3). Furthermore, with the application of Pb(2+) dependent 8-17DNAzyme, the proposed sensing system exhibited high selectivity without using any labeled probes. This biosensor demonstrated a promising potential for Pb(2+) detection in real sample. Copyright © 2015 Elsevier B.V. All rights reserved.

Catalytic reduction of hexavalent chromium by a novel nitrogen-functionalized magnetic ordered mesoporous carbon doped with Pd nanoparticles.

PubMed

Li, Sisi; Tang, Lin; Zeng, Guangming; Wang, Jiajia; Deng, Yaocheng; Wang, Jingjing; Xie, Zhihong; Zhou, Yaoyu

2016-11-01

Hexavalent chromium Cr(VI) is a toxic water pollutant which can cause serious influence to the health of the human and animals. Therefore, developing new methods to remove hexavalent chromium in water attracts great attention of scholars. In our research, we successfully synthesized a new type of magnetic mesoporous carbon hybrid nitrogen (Fe-NMC) loaded with catalyst Pd nanoparticles (NPs), which performed excellent catalytic reduction efficiency toward Cr(VI). The characterization of Pd/Fe-NMC composite was investigated in detail using scanning electron microscope (SEM), high-resolution transmission electron microscopy (HRTEM), Fourier transform infrared spectroscopy (FTIR), and nitrogen adsorption-desorption measurements. According to the experimental results, we dealt with in-depth discussion and studied on the mechanism of hexavalent chromium removed by Pd/Fe-NMC composite. Furthermore, the batch experiments were conducted to investigate the catalytic reduction ability of composite. It was found that the chromium reduction process conforms to pseudo-first-order reaction kinetics model when the concentrations of chromium and sodium formate were low. It took only 20 min for the Pd/Fe-NMC composite to reach 99.8 % reduction of Cr(VI) (50 mg/L). The results suggested that the Pd/Fe-NMC composite may exhibit significantly improved catalytic activity for the hexavalent chromium reduction at industrial wastewater.

Preparation of capacitor's electrode from sunflower seed shell.

PubMed

Li, Xiao; Xing, Wei; Zhuo, Shuping; Zhou, Jin; Li, Feng; Qiao, Shi-Zhang; Lu, Gao-Qing

2011-01-01

Series of nanoporous carbons are prepared from sunflower seed shell (SSS) by two different strategies and used as electrode material for electrochemical double-layer capacitor (EDLC). The surface area and pore-structure of the nanoporous carbons are characterized intensively using N2 adsorption technique. The results show that the pore-structure of the carbons is closely related to activation temperature and dosage of KOH. Electrochemical measurements show that the carbons made by impregnation-activation process have better capacitive behavior and higher capacitance retention ratio at high drain current than the carbons made by carbonization-activation process, which is due to that there are abundant macroscopic pores and less interior micropore surface in the texture of the former. More importantly, the capacitive performances of these carbons are much better than ordered mesoporous carbons and commercial wood-based active carbon, thus highlighting the success of preparing high performance electrode material for EDLC from SSS. Copyright © 2010 Elsevier Ltd. All rights reserved.

A Sortase A-Immobilized Mesoporous Hollow Carbon Sphere-Based Biosensor for Detection of Gram-Positive Bacteria

NASA Astrophysics Data System (ADS)

Wang, Hongsu; Luo, Ruiping; Chen, Yang; Si, Qi; Niu, Xiaodi

2018-05-01

A sensor based on mesoporous carbon materials immobilized with sortase A (SrtA) for determination of Staphylococcus aureus (S. aureus) is reported. To prepare the biosensor, we first synthesized carboxyl-functionalized mesoporous hollow carbon spheres, then applied them as carriers for immobilization of SrtA. Based on the catalytic mechanism of SrtA, a highly sensitive, inexpensive, and rapid method was developed for S. aureus detection. The sensor showed a linear response in the bacterial concentration range of 0.125 × 102 colony-forming units (CFU) mL-1 to 2.5 × 102 CFU mL-1, with detection limit as low as 9.0 CFU mL-1. The method was successfully used for quantitative detection of S. aureus in whole milk samples, giving results similar to experimental results obtained from the plate counting method. This biosensor could also be used to detect other Gram-positive bacteria that secrete SrtA.

Nitrogen-doped mesoporous carbons for high performance supercapacitors

NASA Astrophysics Data System (ADS)

Wu, Kai; Liu, Qiming

2016-08-01

The mesoporous carbons have been synthesized by using α-D(+)-Glucose, D-Glucosamine hydrochloride or their mixture as carbon precursors and mesoporous silicas (SBA-15 or MCF) as hard templates. The as-prepared products show a large pore volume (0.59-0.97 cm3 g-1), high surface areas (352.72-1152.67 m2 g-1) and rational nitrogen content (ca. 2.5-3.9 wt.%). The results of electrochemical tests demonstrate that both heteroatom doping and suitable pore structure play a decisive role in the performance of supercapacitors. The representative sample of SBA-15 replica obtained using D-Glucosamine hydrochloride only exhibits high specific capacitance (212.8 F g-1 at 0.5 A g-1) and good cycle durability (86.1% of the initial capacitance after 2000 cycles) in 6 M KOH aqueous electrolyte, which is attributed to the contribution of double layer capacitance and pseudo-capacitance. The excellent electrochemical performance makes it a promising electrode material for supercapacitors.

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

USDA-ARS?s Scientific Manuscript database

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

Hollow Mesoporous Carbon Microparticles and Micromotors with Single Holes Templated by Colloidal Silica-Assisted Gas Bubbles.

PubMed

Huang, Xiaoxi; Zhang, Tao; Asefa, Tewodros

2017-07-01

A simple, new synthetic method that produces hollow, mesoporous carbon microparticles, each with a single hole on its surface, is reported. The synthesis involves unique templates, which are composed of gaseous bubbles and colloidal silica, and poly(furfuryl alcohol) as a carbon precursor. The conditions that give these morphologically unique carbon microparticles are investigated, and the mechanisms that result in their unique structures are proposed. Notably, the amount of colloidal silica and the type of polymer are found to hugely dictate whether or not the synthesis results in hollow asymmetrical microparticles, each with a single hole. The potential application of the particles as self-propelled micromotors is demonstrated. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

PubMed

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

2010-09-24

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

Quasielastic neutron scattering study of water confined in carbon nanopores

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

Chathoth, S. M.; Mamontov, E.; Kolesnikov, A. I.

2011-07-26

Microscopic dynamics of water confined in nanometer and sub-nanometer pores of carbide-derived carbon (CDC) were investigated using quasielastic neutron scattering (QENS). The temperature dependence of the average relaxation time, ‹τ›, exhibits super-Arrhenius behavior that could be described by Vogel-Fulcher-Tammann (VFT) law in the range from 250 K to 190 K; below this temperature, ‹τ› follows Arrhenius temperature dependence. The temperature of the dynamic crossover between the two regimes in water confined in the CDC pores is similar to that observed for water in hydrophobic confinement of the larger size, such as 14 Å ordered mesoporous carbon (CMK) and 16 Åmore » double-wall carbon nanotubes. Thus, the dynamical behavior of water remains qualitatively unchanged even in the very small hydrophobic pores.« less

New general pore size distribution model by classical thermodynamics application: Activated carbon

USGS Publications Warehouse

Lordgooei, M.; Rood, M.J.; Rostam-Abadi, M.

2001-01-01

A model is developed using classical thermodynamics to characterize pore size distributions (PSDs) of materials containing micropores and mesopores. The thermal equation of equilibrium adsorption (TEEA) is used to provide thermodynamic properties and relate the relative pore filling pressure of vapors to the characteristic pore energies of the adsorbent/adsorbate system for micropore sizes. Pore characteristic energies are calculated by averaging of interaction energies between adsorbate molecules and adsorbent pore walls as well as considering adsorbate-adsorbate interactions. A modified Kelvin equation is used to characterize mesopore sizes by considering variation of the adsorbate surface tension and by excluding the adsorbed film layer for the pore size. The modified-Kelvin equation provides similar pore filling pressures as predicted by density functional theory. Combination of these models provides a complete PSD of the adsorbent for the micropores and mesopores. The resulting PSD is compared with the PSDs from Jaroniec and Choma and Horvath and Kawazoe models as well as a first-order approximation model using Polanyi theory. The major importance of this model is its basis on classical thermodynamic properties, less simplifying assumptions in its derivation compared to other methods, and ease of use.

Monodisperse Mesoporous Carbon Nanoparticles from Polymer/Silica Self-Aggregates and Their Electrocatalytic Activities.

PubMed

Huang, Xiaoxi; Zhou, Li-Jing; Voiry, Damien; Chhowalla, Manish; Zou, Xiaoxin; Asefa, Tewodros

2016-07-27

In our quest to make various chemical processes sustainable, the development of facile synthetic routes and inexpensive catalysts can play a central role. Herein we report the synthesis of monodisperse, polyaniline (PANI)-derived mesoporous carbon nanoparticles (PAMCs) that can serve as efficient metal-free electrocatalysts for the hydrogen peroxide reduction reaction (HPRR) as well as the oxygen reduction reaction (ORR) in fuel cells. The materials are synthesized by polymerization of aniline with the aid of (NH4)2S2O8 as oxidant and colloidal silica nanoparticles as templates, then carbonization of the resulting PANI/silica composite material at different high temperatures, and finally removal of the silica templates from the carbonized products. The PAMC materials that are synthesized under optimized synthetic conditions possess monodisperse mesoporous carbon nanoparticles with an average size of 128 ± 12 nm and an average pore size of ca. 12 nm. Compared with Co3O4, a commonly used electrocatalyst for HPRR, these materials show much better catalytic activity for this reaction. In addition, unlike Co3O4, the PAMCs remain relatively stable during the reaction, under both basic and acidic conditions. The nanoparticles also show good electrocatalytic activity toward ORR. Based on the experimental results, PAMCs' excellent electrocatalytic activity is attributed partly to their heteroatom dopants and/or intrinsic defect sites created by vacancies in their structures and partly to their high porosity and surface area. The reported synthetic method is equally applicable to other polymeric precursors (e.g., polypyrrole (PPY)), which also produces monodisperse, mesoporous carbon nanoparticles in the same way. The resulting materials are potentially useful not only for electrocatalysis of HPRR and ORR in fuel cells but also for other applications where high surface area, small sized, nanostructured carbon materials are generally useful for (e.g., adsorption, supercapacitors, etc.).

Scalable 2D Mesoporous Silicon Nanosheets for High-Performance Lithium-Ion Battery Anode.

PubMed

Chen, Song; Chen, Zhuo; Xu, Xingyan; Cao, Chuanbao; Xia, Min; Luo, Yunjun

2018-03-01

Constructing unique mesoporous 2D Si nanostructures to shorten the lithium-ion diffusion pathway, facilitate interfacial charge transfer, and enlarge the electrode-electrolyte interface offers exciting opportunities in future high-performance lithium-ion batteries. However, simultaneous realization of 2D and mesoporous structures for Si material is quite difficult due to its non-van der Waals structure. Here, the coexistence of both mesoporous and 2D ultrathin nanosheets in the Si anodes and considerably high surface area (381.6 m 2 g -1 ) are successfully achieved by a scalable and cost-efficient method. After being encapsulated with the homogeneous carbon layer, the Si/C nanocomposite anodes achieve outstanding reversible capacity, high cycle stability, and excellent rate capability. In particular, the reversible capacity reaches 1072.2 mA h g -1 at 4 A g -1 even after 500 cycles. The obvious enhancements can be attributed to the synergistic effect between the unique 2D mesoporous nanostructure and carbon capsulation. Furthermore, full-cell evaluations indicate that the unique Si/C nanostructures have a great potential in the next-generation lithium-ion battery. These findings not only greatly improve the electrochemical performances of Si anode, but also shine some light on designing the unique nanomaterials for various energy devices. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Tunneled Mesoporous Carbon Nanofibers with Embedded ZnO Nanoparticles for Ultrafast Lithium Storage.

PubMed

An, Geon-Hyoung; Lee, Do-Young; Ahn, Hyo-Jin

2017-04-12

Carbon and metal oxide composites have received considerable attention as anode materials for Li-ion batteries (LIBs) owing to their excellent cycling stability and high specific capacity based on the chemical and physical stability of carbon and the high theoretical specific capacity of metal oxides. However, efforts to obtain ultrafast cycling stability in carbon and metal oxide composites at high current density for practical applications still face important challenges because of the longer Li-ion diffusion pathway, which leads to poor ultrafast performance during cycling. Here, tunneled mesoporous carbon nanofibers with embedded ZnO nanoparticles (TMCNF/ZnO) are synthesized by electrospinning, carbonization, and postcalcination. The optimized TMCNF/ZnO shows improved electrochemical performance, delivering outstanding ultrafast cycling stability, indicating a higher specific capacity than previously reported ZnO-based anode materials in LIBs. Therefore, the unique architecture of TMCNF/ZnO has potential for use as an anode material in ultrafast LIBs.

The influence of iron oxide nanoparticles upon the adsorption of organic matter on magnetic powdered activated carbon.

PubMed

Lompe, Kim Maren; Menard, David; Barbeau, Benoit

2017-10-15

Combining powdered activated carbon (PAC) with magnetic iron oxides has been proposed in the past to produce adsorbents for natural organic matter (NOM) removal that can be easily separated using a magnetic field. However, the trade-off between the iron oxides' benefits and the reduced carbon content, porosity, and surface area has not yet been investigated systematically. We produced 3 magnetic powdered activated carbons (MPAC) with mass fractions of 10%, 38% and 54% maghemite nanoparticles and compared them to bare PAC and pure nanoparticles with respect to NOM adsorption kinetics and isotherms. While adsorption kinetics were not influenced by the presence of the iron oxide nanoparticles (IONP), as shown by calculated diffusion coefficients from the homogeneous surface diffusion model, nanoparticles reduced the adsorption capacity of NOM due to their lower adsorption capacity. Although the nanoparticles added mesoporosity to the composite materials they blocked intrinsic PAC mesopores at mass fractions >38% as measured by N 2 -adsorption isotherms. Below this mass fraction, the adsorption capacity was mainly dependent on the carbon content in MPAC and mesopore blocking was negligible. If NOM adsorption with MPAC is desired, a highly mesoporous PAC and a low IONP mass fraction should be chosen during MPAC synthesis. Copyright © 2017 Elsevier Ltd. All rights reserved.

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

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

Zhang, Wei-Min, E-mail: chm_zhangwm@ujn.edu.cn; Jiang, Yao-Quan; Cao, Xiao-Yan

2013-10-15

Graphical abstract: - Highlights: • Self-templated synthesis of tubular CdS. • Cadmium complexes of aliphatic acids sustain the network of mesoporous structures. • Aliphatic acids affect the phase composition and particle size. • Pore size and volume vary with aliphatic acids having different hydrocarbonyl. - Abstract: In this study, mesoporous CdS polycrystallites have been synthesized using aliphatic acids of hexanoic acid, octanoic acid, and oleic acid as coordinating and capping agents, respectively. The fibrous Cd–fatty acid salts act as a template to form the tubular CdS. The organic species are found to be necessary for maintaining the network of mesoporousmore » 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.« less

Calcium oxide-modified mesoporous silica loaded onto ferriferrous oxide core: Magnetically responsive mesoporous solid strong base.

PubMed

Li, Tian-Tian; Liu, Yu; Qi, Shi-Chao; Liu, Xiao-Qin; Huang, Li; Sun, Lin-Bing

2018-05-03

The design of new type of solid strong base with ideal activity, stability, and reusability is strongly urged by the growing demand of green chemistry and sustainable development. In this study, a new type of mesoporous solid strong base, denoted as CaO/mSiO 2 /Fe 3 O 4 , is successfully fabricated by successively coating SiO 2 onto Fe 3 O 4 magnetic nanoparticles and loading CaO into the mesoporous SiO 2 . Compared with a series of other typical solid bases, the CaO/mSiO 2 /Fe 3 O 4 exhibits higher activity towards the synthesis of dimethyl carbonate by the transesterification of ethylene carbonate and methanol. The activity of the CaO/mSiO 2 /Fe 3 O 4 is not observed to decrease obviously even after sextic catalyst recirculation, and in particular, the recovery of the catalyst without quality loss is very convenient due to the good magnetic responsiveness of the Fe 3 O 4 cores. Copyright © 2018. Published by Elsevier Inc.

Mesoporous carbon-zirconium oxide nanocomposite derived from carbonized metal organic framework: A coating for solid-phase microextraction.

PubMed

Saraji, Mohammad; Mehrafza, Narges

2016-08-19

In this paper, a mesoporous carbon-ZrO2 nanocomposite was fabricated on a stainless steel wire for the first time and used as the solid-phase microextraction coating. The fiber was synthesized with the direct carbonization of a Zr-based metal organic framework. With the utilization of the metal organic framework as the precursor, no additional carbon source was used for the synthesis of the mesoporous carbon-ZrO2 nanocomposite coating. The fiber was applied for the determination of BTEX compounds (benzene, toluene, ethylbenzene and m, p-xylenes) in different water samples prior to gas chromatography-flame ionization detection. Such important experimental factors as synthesis time and temperature, salt concentration, equilibrium and extraction time, extraction temperature, desorption time and desorption temperature were studied and optimized. Good linearity in the concentration range of 0.2-200μgL(-1) and detection limits in the range of 0.05-0.56μgL(-1) was achieved for BTEX compounds. The intra- and inter-day relative standard deviations were in the range of 3.5-4.8% and 4.9-6.7%, respectively. The prepared fiber showed high capability for the analysis of BTEX compounds in different water and wastewater samples with good relative recoveries in the range of 93-107%. Copyright © 2016 Elsevier B.V. All rights reserved.

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

NASA Astrophysics Data System (ADS)

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

2017-12-01

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

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

PubMed

Hill, Adrian H; Allieta, Mattia

2013-06-14

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

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

PubMed

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

2013-01-01

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.

Ethers as Oxygen Donor and Carbon Source in Non-hydrolytic Sol-Gel: One-Pot, Atom-Economic Synthesis of Mesoporous TiO2 -Carbon Nanocomposites.

PubMed

Escamilla-Pérez, Angel Manuel; Louvain, Nicolas; Boury, Bruno; Brun, Nicolas; Mutin, P Hubert

2018-04-03

Mesoporous TiO 2 -carbon nanocomposites were synthesized using an original non-hydrolytic sol-gel (NHSG) route, based on the reaction of simple ethers (diisopropyl ether or tetrahydrofuran) with titanium tetrachloride. In this atom-economic, solvent-free process, the ether acts not only as an oxygen donor but also as the sole carbon source. Increasing the reaction temperature to 180 °C leads to the decomposition of the alkyl chloride by-product and to the formation of hydrocarbon polymers, which are converted to carbon by pyrolysis under argon. The carbon-TiO 2 nanocomposites and their TiO 2 counterparts (obtained by calcination) were characterized by nitrogen physisorption, XRD, solid state 13 C NMR and Raman spectroscopies, SEM, and TEM. The nanocomposites are mesoporous with surface areas of up to 75 m 2  g -1 and pore sizes around 10 nm. They are composed of aggregated anatase nanocrystals coated by an amorphous carbon film. Playing on the nature of the ether and on the reaction temperature allows control over the carbon content in the nanocomposites. The nature of the ether also influences the size of the TiO 2 crystallites and the morphology of the nanocomposite. To further characterize the carbon coating, the behavior of the carbon-TiO 2 nanocomposites and bare TiO 2 samples toward lithium insertion-deinsertion was investigated in half-cells. This simple NHSG approach should provide a general method for the synthesis of a wide range of carbon-metal oxide nanocomposites. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Fabrication of PdCo Bimetallic Nanoparticles Anchored on Three-Dimensional Ordered N-Doped Porous Carbon as an Efficient Catalyst for Oxygen Reduction Reaction.

PubMed

Xue, Hairong; Tang, Jing; Gong, Hao; Guo, Hu; Fan, Xiaoli; Wang, Tao; He, Jianping; Yamauchi, Yusuke

2016-08-17

PdCo bimetallic nanoparticles (NPs) anchored on three-dimensional (3D) ordered N-doped porous carbon (PdCo/NPC) were fabricated by an in situ synthesis. Within this composite, N-doped porous carbon (NPC) with an ordered mesoporous structure possesses a high surface area (659.6 m(2) g(-1)), which can facilitate electrolyte infiltration. NPC also acts as a perfect 3D conductive network, guaranteeing fast electron transport. In addition, homogeneously distributed PdCo alloy NPs (∼15 nm) combined with the doping of the N element can significantly improve the electrocatalytic activity for the oxygen reduction reaction (ORR). Due to the structural and material superiority, although the weight percentage of PdCo NPs (∼8 wt%) is much smaller than that of commercial Pt/C (20 wt%), the PdCo/NPC catalyst exhibits similar excellent electrocatalytic activity; however, its superior durability and methanol-tolerance ability of the ORR are as great as those of commercial Pt/C in alkaline media.

Preparation and characterization of glycidyl methacrylate organo bridges grafted mesoporous silica SBA-15 as ibuprofen and mesalamine carrier for controlled release.

PubMed

Rehman, Fozia; Rahim, Abdur; Airoldi, Claudio; Volpe, Pedro L O

2016-02-01

Mesoporous silica SBA-15 was synthesized and functionalized with bridged polysilsesquioxane monomers obtained by the reaction of 3-aminopropyltriethoxy silane with glycidyl methacrylate in 2:1 ratio. The synthesized mesoporous silica materials were characterized by elemental analysis, infrared spectroscopy, nuclear magnetic resonance spectroscopy, nitrogen adsorption, X-ray diffraction, thermogravimetry and scanning electron microscopy. The nuclear magnetic resonance in the solid state is in agreement with the sequence of carbon distributed in the attached organic chains, as expected for organically functionalized mesoporous silica. After functionalization with organic bridges the BET surface area was reduced from 1311.80 to 494.2m(2)g(-1) and pore volume was reduced from 1.98 to 0.89cm(3)g(-1), when compared to original precursor silica. Modification of the silica surface with organic bridges resulted in high loading capacity and controlled release of ibuprofen and mesalamine in biological fluids. The Korsmeyer-Peppas model better fits the release data indicating Fickian diffusion and zero order kinetics for synthesized mesoporous silica. The drug release rate from the modified silica was slow in simulated gastric fluid, (pH1.2) where less than 10% of mesalamine and ibuprofen were released in initial 8h, while comparatively high release rates were observed in simulated intestinal (pH6.8) and simulated body fluids (pH7.2). The preferential release of mesalamine at intestinal pH suggests that the modified silica could be a simple, efficient, inexpensive and convenient carrier for colon targeted drugs, such a mesalamine and also as a controlled drug release system. Copyright © 2015 Elsevier B.V. All rights reserved.

Relationship between Structural Characteristics of Activated Carbons and Their Concentrating Efficiency with Respect to Nitroorganics.

PubMed

Leboda, R.; Gun'ko, V. M.; Tomaszewski, W.; Trznadel, B. J.

2001-07-15

The relationships between structural properties of activated microporous, micro-mesoporous, mesoporous, and graphitized carbons determined on the basis of nitrogen adsorption at 77.4 K and the efficiency of concentrating (solid-phase extraction (SPE) technique) several nitroorganic compounds from polar solvents were investigated. Microporosity, mesoporosity, fractality, and other characteristics of adsorbents were analyzed to evaluate the dependence of the effectiveness of the SPE technique with respect to nitrate esters, cyclic nitroamines, and nitroaromatics on the origin and texture of carbons. The values of the free energy of solvation and dipole moment of nitroorganic compounds in polar liquids computed with the SM5.42/PM3 method with consideration of geometry relaxation in solution were utilized to elucidate features of their concentration of carbon adsorbents. Copyright 2001 Academic Press.

Hypercrosslinked phenolic polymers with well developed mesoporous frameworks

DOE PAGES

Zhang, Jinshui; Qiao, Zhenan -An; Mahurin, Shannon Mark; ...

2015-02-12

A soft chemistry synthetic strategy based on a Friedel Crafts alkylation reaction is developed for the textural engineering of phenolic resin (PR) with a robust mesoporous framework to avoid serious framework shrinkage and maximize retention of organic functional moieties. By taking advantage of the structural benefits of molecular bridges, the resultant sample maintains a bimodal micro-mesoporous architecture with well-preserved organic functional groups, which is effective for carbon capture. Furthermore, this soft chemistry synthetic protocol can be further extended to nanotexture other aromatic-based polymers with robust frameworks.

Sructure and dynamics of fluids in micropous and mesoporous earth and engineered materials

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

Cole, David R; Mamontov, Eugene; Rother, Gernot

2009-01-01

The behavior of liquids in confined geometries (pores, fractures) typically differs, due to the effects of large internal surfaces and geometri-cal confinement, from their bulk behavior in many ways. Phase transitions (i.e., freezing and capillary condensation), sorption and wetting, and dy-namical properties, including diffusion and relaxation, may be modified, with the strongest changes observed for pores ranging in size from <2 nm to 50 nm the micro- and mesoporous regimes. Important factors influ-encing the structure and dynamics of confined liquids include the average pore size and pore size distribution, the degree of pore interconnection, and the character of the liquid-surfacemore » interaction. While confinement of liq-uids in hydrophobic matrices, such as carbon nanotubes, or near the sur-faces of mixed character, such as many proteins, has also been an area of rapidly growing interest, the confining matrices of interest to earth and ma-terials sciences usually contain oxide structural units and thus are hydro-philic. The pore size distribution and the degree of porosity and inter-connection vary greatly amongst porous matrices. Vycor, xerogels, aerogels, and rocks possess irregular porous structures, whereas mesopor-ous silicas (e.g., SBA-15, MCM-41, MCM-48), zeolites, and layered sys-tems, for instance clays, have high degrees of internal order. The pore type and size may be tailored by means of adjusting the synthesis regimen. In clays, the interlayer distance may depend on the level of hydration. Al-though studied less frequently, matrices such as artificial opals and chry-sotile asbestos represent other interesting examples of ordered porous structures. The properties of neutrons make them an ideal probe for com-paring the properties of bulk fluids with those in confined geometries. In this chapter, we provide a brief review of research performed on liquids confined in materials of interest to the earth and material sciences (silicas, aluminas, zeolites, clays, rocks, etc.), emphasizing those neutron scattering techniques which assess both structural modification and dynamical behav-ior. Quantitative understanding of the complex solid-fluid interactions under different thermodynamic situations will impact both the design of bet-ter substrates for technological applications (e.g., chromatography, fluid capture, storage and release, and heterogeneous catalysis) as well as our fundamental understanding of processes encountered in the environment (i.e., fluid and waste mitigation, carbon sequestration, etc.).« less

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

NASA Astrophysics Data System (ADS)

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

2015-03-01

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

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

NASA Astrophysics Data System (ADS)

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

2017-11-01

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

Adsorption of an anionic dye on a novel low-cost mesoporous adsorbent: kinetic, thermodynamic and isotherm studies

NASA Astrophysics Data System (ADS)

Msaad, Asmaa; Belbahloul, Mounir; Zouhri, Abdeljalil

2018-05-01

Our activated carbon was prepared successfully using phosphoric acid as an activated agent. The activated carbon was characterized by Scanning Electron Micrograph (SEM), Brunauer-Emmett- Teller (BET), Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD). The aim of our study is to evaluate the adsorption capacity of Methyl Orange (MO) on Ziziphus lotus activated carbon. Adsorption isotherms were studied according to Langmuir and Freundlich Model, and adsorption kinetics according to pseudo-first and second-order. Results show that the maximum adsorption was reached in the first 10min at ambient temperature with a yield of 96.31%. The Langmuir isotherm shows a correlation coefficient of 99.4 % higher than Freundlich model and the adsorption kinetic model follow a pseudo-second-order with a maximum adsorption capacity of 769.23 mg/g. FTIR and X-Ray spectroscopy indicate that our activated carbon has an amorphous structure with the presence of functional groups, where BET analysis revealed a high surface area of 553 mg/g, which facilitate the adsorption process

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

NASA Astrophysics Data System (ADS)

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

2016-08-01

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

Mesoporous carbons and polymers

DOEpatents

Bell, William; Dietz, Steven

2001-01-01

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

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

PubMed

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

2018-02-01

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

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

PubMed Central

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

2013-01-01

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

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

PubMed

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

2015-02-01

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

Highly electroconductive mesoporous graphene nanofibers and their capacitance performance at 4 V.

PubMed

Cui, Chaojie; Qian, Weizhong; Yu, Yuntao; Kong, Chuiyan; Yu, Bo; Xiang, Lan; Wei, Fei

2014-02-12

We report the fabrication of one-dimensional highly electroconductive mesoporous graphene nanofibers (GNFs) by a chemical vapor deposition method using MgCO3·3H2O fibers as the template. The growth of such a unique structure underwent the first in situ decomposition of MgCO3·3H2O fibers to porous MgO fibers, followed by the deposition of carbon on the MgO surface, the removal of MgO by acidic washing, and the final self-assembly of wet graphene from single to double layer in drying process. GNFs exhibited good structural stability, high surface area, mesopores in large amount, and electrical conductivity 3 times that of carbon nanotube aggregates. It, used as an electrode in a 4 V supercapacitor, exhibited high energy density in a wide range of high power density and excellent cycling stability. The short diffusion distance for ions of ionic liquids electrolyte to the surface of GNFs yielded high surface utilization efficiency and a capacitance up to 15 μF/cm(2), higher than single-walled carbon nanotubes.

Mesoporous cellular-structured carbons derived from glucose-fructose syrup and their adsorption properties towards acetaminophen

NASA Astrophysics Data System (ADS)

Tzvetkov, George; Spassov, Tony; Kaneva, Nina; Tsyntsarski, Boyko

Here, a series of cellular-structured and predominantly mesoporous carbons were prepared via carbonization of glucose-fructose syrup (GFS) with sulfuric acid and subsequent calcination between 400∘C and 700∘C. Comparative results on the microstructure, chemical and textural properties of the newly produced carbons are presented. Furthermore, their adsorption performance for removal of acetaminophen from water was tested and it was found that the carbon calcined at 700∘C has a maximum adsorption capacity (98.7mgṡg-1) among all samples due to its suitable textural properties (BET surface area of 418m2ṡg-1 and total pore volume of 0.2cm3ṡg-1). This study demonstrates the potential use of GFS as a precursor in the preparation of carbonaceous materials for removal of biologically-active micropollutants from water.

A Review of Recent Developments of Mesoporous Materials.

PubMed

Suib, Steven L

2017-12-01

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

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

PubMed

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

2016-03-08

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

Research on the Ordered Mesoporous Silica for Tobacco Harm Reduction

NASA Astrophysics Data System (ADS)

Wang, Y.; Y Li, Z.; Ding, J. X.; Hu, Z. J.; Liu, Z.; Zhou, G.; Huang, T. H.

2017-12-01

For reducting tobacco harm, this paper prepared an ordered mesoporous silica by using triblock copolymer Pluronic P123 as template. The property of this material was characterized by the X-ray scattering spectrum(XRD), Transmission electron microscopy(TEM), Scanning electron microscopy (SEM) and Nitrogen adsorption/desorption. Then this ordered mesoporous silica was added into the cigarette filter in order to researching its effect of cigarette harm index. The result shows that the feature of SBA-15 was grain morphology, ordered arrangement, tubular porous 2-D hexagonal structure. The application of SBA-15 in cigarette filter can selectively reduce harmful components in cigarette smoke such as crotonaldehyde, hydrogen cyanide, benzo pyrene and tar. The synthesized SBA-15 could properly reduce cigarette harm index.

MnO2-graphene nanosheets wrapped mesoporous carbon/sulfur composite for lithium-sulfur batteries

NASA Astrophysics Data System (ADS)

Li, Zhengzheng

2018-02-01

MnO2-graphene nanosheets wrapped mesoporous carbon/sulfur (MGN@MC/S) composite is successfully synthesized derived from metal-organic frameworks and investigated as cathode for lithium-ion batteries. Used as cathode, MGN@MC/S composite possesses electronic conductivity network for redox electron transfer and strong chemical bonding to lithium polysulfides, which enables low capacity loss to be achieved. MGN@MC/S cathodes exhibit high reversible capacity of 1475 mA h g-1 at 0.1 C and an ultra-low capacity fading of 0.042% per cycle at 1 C over 450 cycles.

Superior lithium electroactive mesoporous Si@carbon core-shell nanowires for lithium battery anode material.

PubMed

Kim, Hyesun; Cho, Jaephil

2008-11-01

Mesoporous Si@carbon core-shell nanowires with a diameter of approximately 6.5 nm were prepared for a lithium battery anode material using a SBA-15 template. As-synthesized nanowires demonstrated excellent first charge capacity of 3163 mA h/g with a Coulombic efficiency of 86% at a rate of 0.2 C (600 mA/g) between 1.5 and 0 V in coin-type half-cells. Moreover, the capacity retention after 80 cycles was 87% and the rate capability at 2 C (6000 mA/g) was 78% the capacity at 0.2 C.

Ordered mesoporous ternary mixed oxide materials as potential adsorbent of biomolecules

NASA Astrophysics Data System (ADS)

Pal, Nabanita; Bhaumik, Asim

2012-05-01

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

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

NASA Astrophysics Data System (ADS)

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

2014-01-01

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

Location of laccase in ordered mesoporous materials

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

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

2014-11-01

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

Location of laccase in ordered mesoporous materials

NASA Astrophysics Data System (ADS)

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

2014-11-01

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

Highly porous activated carbons from resource-recovered Leucaena leucocephala wood as capacitive deionization electrodes.

PubMed

Hou, Chia-Hung; Liu, Nei-Ling; Hsi, Hsing-Cheng

2015-12-01

Highly porous activated carbons were resource-recovered from Leucaena leucocephala (Lam.) de Wit. wood through combined chemical and physical activation (i.e., KOH etching followed by CO2 activation). This invasive species, which has severely damaged the ecological economics of Taiwan, was used as the precursor for producing high-quality carbonaceous electrodes for capacitive deionization (CDI). Carbonization and activation conditions strongly influenced the structure of chars and activated carbons. The total surface area and pore volume of activated carbons increased with increasing KOH/char ratio and activation time. Overgasification induced a substantial amount of mesopores in the activated carbons. In addition, the electrochemical properties and CDI electrosorptive performance of the activated carbons were evaluated; cyclic voltammetry and galvanostatic charge/discharge measurements revealed a typical capacitive behavior and electrical double layer formation, confirming ion electrosorption in the porous structure. The activated-carbon electrode, which possessed high surface area and both mesopores and micropores, exhibited improved capacitor characteristics and high electrosorptive performance. Highly porous activated carbons derived from waste L. leucocephala were demonstrated to be suitable CDI electrode materials. Copyright © 2015 Elsevier Ltd. All rights reserved.

Nanocrystal-constructed mesoporous CoFe₂O₄ nanowire arrays aligned on flexible carbon fabric as integrated anodes with enhanced lithium storage properties.

PubMed

Wang, Bo; Li, Songmei; Wu, Xiaoyu; Li, Bin; Liu, Jianhua; Yu, Mei

2015-09-07

A novel and facile two-step strategy is successfully developed for the large-scale fabrication of hierarchical mesoporous CoFe2O4 nanowire arrays (NWAs) on flexible carbon fabric as integrated anodes for highly efficient and reversible lithium storage. The synthesis involves the co-deposition of uniform bimetallic (Co, Fe) carbonate hydroxide hydrate precursor NWAs on carbon fabric and subsequent thermal transformation to spinel CoFe2O4 without damaging the morphology. The as-prepared CoFe2O4 nanowires have unique mesoporous structures, which are constructed by many interconnected nanocrystals with sizes of about 15-20 nm. The typical size of the nanowires is in the range of 70-100 nm in width and up to several micrometers in length. Such a hybrid nanostructure electrode presented here not only simplifies electrode processing, but also promises fast electron transport/collection and ion diffusion, and withstands volume variation upon prolonged charge/discharge cycling. As a result, the binder-free CoFe2O4/carbon fabric composite exhibits a high reversible capacity of 1185.75 mA h g(-1) at a current density of 200 mA g(-1), and a superior rate capability. More importantly, a reversible capacity as high as ∼950 mA h g(-1) can be retained and there is no obvious decay after 150 cycles.

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

PubMed

Li, Daohao; Lv, Chunxiao; Liu, Long; Xia, Yanzhi; She, Xilin; Guo, Shaojun; Yang, Dongjiang

2015-08-26

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

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

PubMed Central

2015-01-01

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

Versatile NiO/mesoporous carbon nanodisks: controlled synthesis from hexagon shaped heterobimetallic metal-organic frameworks.

PubMed

Zeng, Dehong; Yang, Ying; Yang, Feng; Guo, Fangmin; Yang, Senjie; Liu, Baijun; Hao, Shijie; Ren, Yang

2017-08-24

Hexagonal NiO/mesoporous carbon nanodisks (NiO/MCN) are facilely and controllably synthesized via constructing nickel-zinc trimesic acid heterobimetallic metal-organic framework (HMOF) disks before pyrolysis at 910 °C. Tailoring the Ni/(Zn + Ni) feed ratio and the reaction time during the HMOF synthesis creates a well-defined hexagonal carbon nanodisk with properly populated NiO nanocrystals while maintaining high porosity and conductivity. Such an elaborately fabricated NiO/MCN is highly stable, and exhibits the largest specific capacitance of 261 F g -1 and the highest specific activity factor of 1.93 s -1 g -1 of any composite nanodisk during the capacitive test and 4-nitrophenol reduction, respectively.

Open-cage fullerene-like graphitic carbons as catalysts for oxidative dehydrogenation of isobutane.

PubMed

Liang, Chengdu; Xie, Hong; Schwartz, Viviane; Howe, Jane; Dai, Sheng; Overbury, Steven H

2009-06-10

We report herein a facile synthesis of fullerene-like cages, which can be opened and closed through simple thermal treatments. A glassy carbon with enclosed fullerene-like cages of 2-3 nm was synthesized through a soft-template approach that created open mesopores of 7 nm. The open mesopores provided access to the fullerene-like cages, which were opened and closed through heat treatments in air and inert gas at various temperatures. Catalytic measurements showed that the open cages displayed strikingly higher activity for the oxidative dehydrogenation of isobutane in comparison to the closed ones. We anticipate that this synthesis approach could unravel an avenue for pursuing fundamental understanding of the unique catalytic properties of graphitic carbon nanostructures.

High performance sulfur, nitrogen and carbon doped mesoporous anatase-brookite TiO₂ photocatalyst for the removal of microcystin-LR under visible light irradiation.

PubMed

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

2014-09-15

Carbon, nitrogen and sulfur (C, N and S) doped mesoporous anatase-brookite nano-heterojunction titania photocatalysts have been synthesized through a simple sol-gel method in the presence of triblock copolymer Pluronic P123. XRD and Raman spectra revealed the formation of anatase and brookite mixed phases. XPS spectra indicated the presence of C, N and S dopants. The TEM images demonstrated the formation of almost monodisperse titania nanoparticles with particle sizes of approximately 10nm. N2 isotherm measurements confirmed that both doped and undoped titania anatase-brookite materials have mesoporous structure. The photocatalytic degradation of the cyanotoxin microcystin-LR (MC-LR) has been investigated using these novel nanomaterials under visible light illumination. The photocatalytic efficiency of the mesoporous titania anatase-brookite photocatalyst dramatically increased with the addition of the C, N and S non-metal, achieving complete degradation (∼ 100 %) of MC-LR. The results demonstrate the advantages of the synthetic approach and the great potential of the visible light activated C, N, and S doped titania photocatalysts for the treatment of organic micropollutants in contaminated waters under visible light. Copyright © 2014 Elsevier B.V. All rights reserved.

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

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

Chouyyok, Wilaiwan; Yantasee, Wassana; Shin, Yongsoon

2009-11-01

Functional mesoporous carbon has been built using 1,10-phenanthroline as the fundamental building block, resulting in a nanoporous, high surface area sorbent capable of selectively binding transition metal ions. This material had a specific surface area of 870 m2/g, an average pore size of about 30Å, and contained as much as 8.2 weight percent N. Under acidic conditions, where the 1,10-phenanthroline ligand is protonated, this material was found to be an effective anion exchange material for transition metal anions like PdCl4-2 and H2VO4-1. 1,10-phenanthroline functionalized mesoporous carbon (“Phen-FMC”) was found to have a high affinity for Cu(II), even down to amore » pH of 1. At pHs above 5, Phen-FMC was found to bind a variety of transition metal cations (e.g. Co(II), Ni(II), Zn(II), etc.) from filtered ground water, river water and seawater. Phen-FMC displayed rapid sorption kinetics with Co(II) in filtered river water, reaching equilibrium in less than an hour, and easily lowering the [Co(II)] to sub-ppb levels. Phen-FMC was found to be more effective for transition metal ion capture than ion exchange resin or activated carbon.« less

Tunable conductivity in mesoporous germanium

NASA Astrophysics Data System (ADS)

Beattie, Meghan N.; Bioud, Youcef A.; Hobson, David G.; Boucherif, Abderraouf; Valdivia, Christopher E.; Drouin, Dominique; Arès, Richard; Hinzer, Karin

2018-05-01

Germanium-based nanostructures have attracted increasing attention due to favourable electrical and optical properties, which are tunable on the nanoscale. High densities of germanium nanocrystals are synthesized via electrochemical etching, making porous germanium an appealing nanostructured material for a variety of applications. In this work, we have demonstrated highly tunable electrical conductivity in mesoporous germanium layers by conducting a systematic study varying crystallite size using thermal annealing, with experimental conductivities ranging from 0.6 to 33 (×10‑3) Ω‑1 cm‑1. The conductivity of as-prepared mesoporous germanium with 70% porosity and crystallite size between 4 and 10 nm is shown to be ∼0.9 × 10‑3 Ω‑1 cm‑1, 5 orders of magnitude smaller than that of bulk p-type germanium. Thermal annealing for 10 min at 400 °C further reduced the conductivity; however, annealing at 450 °C caused a morphological transformation from columnar crystallites to interconnecting granular crystallites and an increase in conductivity by two orders of magnitude relative to as-prepared mesoporous germanium caused by reduced influence of surface states. We developed an electrostatic model relating the carrier concentration and mobility of p-type mesoporous germanium to the nanoscale morphology. Correlation within an order of magnitude was found between modelled and experimental conductivities, limited by variation in sample uniformity and uncertainty in void size and fraction after annealing. Furthermore, theoretical results suggest that mesoporous germanium conductivity could be tuned over four orders of magnitude, leading to optimized hybrid devices.

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

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

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

2012-12-15

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

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

NASA Astrophysics Data System (ADS)

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

2010-05-01

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

Templated synthesis of highly ordered mesoporous cobalt ferrite and its microwave absorption properties

NASA Astrophysics Data System (ADS)

Li, Guo-Min; Wang, Lian-Cheng; Xu, Yao

2014-08-01

Based on the nanocasting strategy, highly ordered mesoporous CoFe2O4 is synthesized via the ‘two-solvent’ impregnation method using a mesoporous SBA-15 template. An ordered two-dimensional (P6mm) structure is preserved for the CoFe2O4/SBA-15 composite after the nanocasting. After the SBA-15 template is dissolved by NaOH solution, a mesoporous structure composed of aligned nanoparticles can be obtained, and the P6mm structure of the parent SBA-15 is preserved. With a high specific surface area (above 90 m2/g) and ferromagnetic behavior, the obtained material shows potential in light weight microwave absorption application. The minimum reflection loss (RL) can reach -18 dB at about 16 GHz with a thickness of 2 mm and the corresponding absorption bandwidth is 4.5 GHz.

Influence of carbon content on photocatalytic performance of C@ZnO hollow nanospheres

NASA Astrophysics Data System (ADS)

Jin, Changqing; Zhu, Kexin; Jian, Zengyun; Wei, Yongxing; Gao, Ling; Zhang, Zhihong; Zheng, Deshan

2018-02-01

Mesoporous C@ZnO hollow spheres were successfully synthesized through a carbon-sphere template combined hydrothermal method. The photocatalytic activities of the samples to rhodamine B (RhB) were investigated, and the sample of 3 wt% carbon has the best photocatalytic activity to RhB. The excellent photocatalytic performance could come from both enhanced photogenerated electron-hole pair separation, and the larger specific surface area induced by mesoporous hollow nanostructure. The photocatalytic performance sensitively depends upon content of amorphous carbon. Too much or too little carbon content decreases sample performance. The changes in performance according to carbon content are probably a result of the competing mechanism: the increasing rate of separation efficiency of photogenerated carriers and the decreasing contact area of ZnO with RhB according to the carbon content. This work would help us to better understand the important roles of carbon content in the fabricated nano-heterojunctions and also provide us with a feasible route to improve UV photocatalytic activities of ZnO and other metal oxides greatly.

Performance of different carbonaceous materials for emerging pollutants adsorption.

PubMed

Patiño, Yolanda; Díaz, Eva; Ordóñez, Salvador

2015-01-01

The adsorption of three representative emerging pollutants over different kinds of carbonaceous adsorbents has been studied in this work. The adsorbates were nalidixic acid (NAL, representative of a pharmaceutical), 1,8-dichlorooctane (DCO, a chloroparaffin) and methyl-phenoxy-ethanol (MPET, a surfactant). Activated carbons, carbon nanofibers, carbon nanotubes and high surface area graphites have been tested as adsorbents. Adsorption isotherms, carried out in a batch system, were fitted using both a Langmuir and a Freundlich model. It was shown that the capacity of adsorption follows the order DCO≫NAL>MPET for all the adsorbents, and among the adsorbents, the external morphology (surface area and mesoporous volume) is the key parameter. The results from thermodynamic analysis show, however, that both morphological and chemical properties of both adsorbates and adsorbents influenced their behavior. Copyright © 2014 Elsevier Ltd. All rights reserved.

Adsorption of microcystin-LR on mesoporous carbons and its potential use in drinking water source.

PubMed

Park, Jeong-Ann; Jung, Sung-Mok; Yi, In-Geol; Choi, Jae-Woo; Kim, Song-Bae; Lee, Sang-Hyup

2017-06-01

Microcystin-LR (MC-LR) is a common toxin derived from cyanobacterial blooms an effective, rapid and non-toxic method needs to be developed for its removal from drinking water treatment plants (DWTP). For an adsorption-based method, mesoporous carbon can be a promising supplemental adsorbent. The effect of mesoporous carbon (MC1, MC2, and MC3) properties and water quality parameters on the adsorption of MC-LR were investigated and the results were analyzed by kinetic, isotherm, thermodynamic, Derjaguin-Landau-Verwey-Overbeek (DLVO), and intraparticle diffusion models. MC1 was the most appropriate type for the removal of MC-LR with a maximum adsorption capacity of 35,670.49 μg/g. Adsorption of MC-LR is a spontaneous reaction dominated by van der Waals interactions. Pore sizes of 8.5-14 nm enhance the pore diffusion of MC-LR from the surface to the mesopores of MC1. The adsorption capacity was not sensitive to changes in the pH (3.2-8.0) and the existence of organic matter (2-5 mg/L). Furthermore, the final concentration of MC-LR was below the WHO guideline level after a 10-min reaction with 20 mg/L of MC1 in the Nak-Dong River, a drinking water source. The MC-LR adsorption mainly competed with humic substances (500-1000 g/mole); however, they did not have a great effect on adsorption. Copyright © 2017. Published by Elsevier Ltd.

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)

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

2014-05-01

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.

The Effect of CO2 Activation on the Electrochemical Performance of Coke-Based Activated Carbons for Supercapacitors.

PubMed

Lee, Hye-Min; Kim, Hong-Gun; An, Kay-Hyeok; Kim, Byung-Joo

2015-11-01

The present study developed electrode materials for supercapacitors by activating coke-based activated carbons with CO2. For the activation reaction, after setting the temperature at 1,000 degrees C, four types of activated carbons were produced, over an activation time of 0-90 minutes and with an interval of 30 minutes as the unit. The electrochemical performance of the activated carbons produced was evaluated to examine the effect of CO2 activation. The surface structure of the porous carbons activated through CO2 activation was observed using a scanning electron microscope (SEM). To determine the N2/77 K isothermal adsorption characteristics, the Brunauer-Emmett-Teller (BET) equation and the Barrett-Joyner-Halenda (BJH) equation were used to analyze the pore characteristics. In addition, charge and discharge tests and cyclic voltammetry (CV) were used to analyze the electrochemical characteristics of the changed pore structure. According to the results of the experiments, the N2 adsorption isotherm curves of the porous carbons produced belonged to Type IV in the International Union of Pore and Applied Chemistry (IUPAC) classification and consisted of micropores and mesopores, and, as the activation of CO2 progressed, micropores decreased and mesopores developed. The specific surface area of the porous carbons activated by CO2 was 1,090-1,180 m2/g and thus showed little change, but those of mesopores were 0.43-0.85 cm3/g, thus increasing considerably. In addition, when the electrochemical characteristics were analyzed, the specific capacity was confirmed to have increased from 13.9 F/g to 18.3 F/g. From these results, the pore characteristics of coke-based activated carbons changed considerably because of CO2 activation, and it was therefore possible to increase the electrochemical characteristics.

Understanding Acoustic Cavitation Initiation by Porous Nanoparticles: Toward Nanoscale Agents for Ultrasound Imaging and Therapy.

PubMed

Yildirim, Adem; Chattaraj, Rajarshi; Blum, Nicholas T; Goodwin, Andrew P

2016-08-23

Ultrasound is widely applied in medical diagnosis and therapy due to its safety, high penetration depth, and low cost. In order to improve the contrast of sonographs and efficiency of the ultrasound therapy, echogenic gas bodies or droplets (with diameters from 200 nm to 10 µm) are often used, which are not very stable in the bloodstream and unable to penetrate into target tissues. Recently, it was demonstrated that nanobubbles stabilized by nanoparticles can nucleate ultrasound responsive microbubbles under reduced acoustic pressures, which is very promising for the development of nanoscale (<100 nm) ultrasound agents. However, there is still very little understanding about the effects of nanoparticle properties on the stabilization of nanobubbles and nucleation of acoustic cavitation by these nanobubbles. Here, a series of mesoporous silica nanoparticles with sizes around 100 nm but with different morphologies were synthesized to understand the effects of nanoparticle porosity, surface roughness, hydrophobicity, and hydrophilic surface modification on acoustic cavitation inception by porous nanoparticles. The chemical analyses of the nanoparticles showed that, while the nanoparticles were prepared using the same silica precursor (TEOS) and surfactant (CTAB), they revealed varying amounts of carbon impurities, hydroxyl content, and degrees of silica crosslinking. Carbon impurities or hydrophobic modification with methyl groups is found to be essential for nanobubble stabilization by mesoporous silica nanoparticles. The acoustic cavitation experiments in the presence of ethanol and/or bovine serum albumin (BSA) demonstrated that acoustic cavitation is predominantly nucleated by the nanobubbles stabilized at the nanoparticle surface not inside the mesopores. Finally, acoustic cavitation experiments with rough and smooth nanoparticles were suggested that a rough nanoparticle surface is needed to largely preserve surface nanobubbles after coating the surface with hydrophilic macromolecules, which is required for in vivo applications of nanoparticles.

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

PubMed Central

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

2013-01-01

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

Hard template synthesis of metal nanowires

PubMed Central

Kawamura, Go; Muto, Hiroyuki; Matsuda, Atsunori

2014-01-01

Metal nanowires (NWs) have attracted much attention because of their high electron conductivity, optical transmittance, and tunable magnetic properties. Metal NWs have been synthesized using soft templates such as surface stabilizing molecules and polymers, and hard templates such as anodic aluminum oxide, mesoporous oxide, carbon nanotubes. NWs prepared from hard templates are composites of metals and the oxide/carbon matrix. Thus, selecting appropriate elements can simplify the production of composite devices. The resulting NWs are immobilized and spatially arranged, as dictated by the ordered porous structure of the template. This avoids the NWs from aggregating, which is common for NWs prepared with soft templates in solution. Herein, the hard template synthesis of metal NWs is reviewed, and the resulting structures, properties and potential applications are discussed. PMID:25453031

Hard template synthesis of metal nanowires

NASA Astrophysics Data System (ADS)

Kawamura, Go; Muto, Hiroyuki; Matsuda, Atsunori

2014-11-01

Metal nanowires (NWs) have attracted much attention because of their high electron conductivity, optical transmittance and tunable magnetic properties. Metal NWs have been synthesized using soft templates such as surface stabilizing molecules and polymers, and hard templates such as anodic aluminum oxide, mesoporous oxide, carbon nanotubes. NWs prepared from hard templates are composites of metals and the oxide/carbon matrix. Thus, selecting appropriate elements can simplify the production of composite devices. The resulting NWs are immobilized and spatially arranged, as dictated by the ordered porous structure of the template. This avoids the NWs from aggregating, which is common for NWs prepared with soft templates in solution. Herein, the hard template synthesis of metal NWs is reviewed, and the resulting structures, properties and potential applications are discussed.

Hard template synthesis of metal nanowires.

PubMed

Kawamura, Go; Muto, Hiroyuki; Matsuda, Atsunori

2014-01-01

Metal nanowires (NWs) have attracted much attention because of their high electron conductivity, optical transmittance, and tunable magnetic properties. Metal NWs have been synthesized using soft templates such as surface stabilizing molecules and polymers, and hard templates such as anodic aluminum oxide, mesoporous oxide, carbon nanotubes. NWs prepared from hard templates are composites of metals and the oxide/carbon matrix. Thus, selecting appropriate elements can simplify the production of composite devices. The resulting NWs are immobilized and spatially arranged, as dictated by the ordered porous structure of the template. This avoids the NWs from aggregating, which is common for NWs prepared with soft templates in solution. Herein, the hard template synthesis of metal NWs is reviewed, and the resulting structures, properties and potential applications are discussed.

Impregnation of Fenofibrate on mesoporous silica using supercritical carbon dioxide.

PubMed

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

2016-02-29

Low oral bioavailability can be circumvented by the formulation of the poorly water soluble drug in ordered mesoporous silica (OMS-L-7). Fenofibrate is an orally administered, poorly water-soluble active pharmaceutical ingredient (API), used clinically to lower lipid levels. Fenofibrate was loaded into silica using two methods: incipient wetness and supercritical impregnation. This study investigates the impact of loading and the impact of varying supercritical carbon dioxide (scCO2) processing conditions. The objective is to enhance Fenofibrate loading into silica while reducing degree of the drug crystallinity, so as to increase the drug's dissolution rate and its bioavailability. The comparison of both impregnation processes was made in terms of impregnation yields and duration as well as physical characterization of the drug. While incipient wetness method led to a Fenofibrate loading up to 300 mgdrug/gsilica in 48 h of impregnation, the supercritical impregnation method yielded loading up to 485 mgdrug/gsilica in 120 min of impregnation duration, at 16 MPa and 308 K, with a low degree of crystallinity (about 1%) comparable to the crystallinity observed via the solvent method. In addition to the enhancement of impregnation efficiency, the supercritical route provides a solvent-free alternative for impregnation. Copyright © 2015 Elsevier B.V. All rights reserved.

Templated Growth of Carbon Nanotubes

NASA Technical Reports Server (NTRS)

Siochik Emilie J. (Inventor)

2007-01-01

A method of growing carbon nanotubes uses a synthesized mesoporous si lica template with approximately cylindrical pores being formed there in. The surfaces of the pores are coated with a carbon nanotube precu rsor, and the template with the surfaces of the pores so-coated is th en heated until the carbon nanotube precursor in each pore is convert ed to a carbon nanotube.

Effect of rate of pyrolysis on the textural properties of naturally-templated porous carbons from alginic acid.

PubMed

Marriott, Andrew S; Hunt, Andrew J; Bergström, Ed; Thomas-Oates, Jane; Clark, James H

2016-09-01

The effect of pyrolysis rate on the properties of alginic acid-derived carbonaceous materials, termed Starbon ® , was investigated. Thermal Gravimetry-IR was used to prepare porous carbons up to 800 °C at several rates and highlighted increased CO 2 production at higher pyrolysis rates. N 2 porosimetry of the resultant carbons shows how pyrolysis rate affects both the mesopore structure and thus surface area and surface energy. Surface capacity of these carbons was analysed by methylene blue dye adsorption. In general, as the rate of pyrolysis increased, the mesopore content and adsorbent capacity decreased. It is considered here that the rapid production of volatiles at these higher rates causes structural collapse of the non-templated pore network. The work here demonstrates that pyrolysis rate is a key variable which needs to be controlled to maximise the textural properties of Starbon ® required for adsorption applications.

General and simple approach for control cage and cylindrical mesopores, and thermal/hydrothermal stable frameworks.

PubMed

El-Safty, Sherif A; Mizukami, Fujio; Hanaoka, Takaaki

2005-05-19

Highly ordered cage and cylindrical mesoporeous silica monoliths (HOM) with 2- and 3-dimensional (2D and 3D, respectively) structures, mesopore/micropore volumes, and thick-walled frameworks were successfully fabricated by instant direct templating of lyotropic phases of copolymer (EO(m)-PO(n)-EO(m)) surfactants. Large cage-like pores with uniform constriction sizes up to 10 nm and open cylindrical channel-like mesopores can be easily achieved by this simple and efficient synthesis design. Our results show that the cage-like pores could be fabricated at relatively lower copolymer concentrations used in the lyotropic phase domains at copolymer/TMOS ratios of 35 wt %. These ordered cage pore architectures underwent transition to open-cylindrical pores by increasing the copolymer concentration. High EO/PO block copolymers, in general, were crucially affected on the increase of the interior cavity sizes and on the stability of the cage mesopore characters. However, for F108 (EO(141)PO(44)EO(141)) systems, the fabrication of ordered and stable cage pore monoliths was achieved with significantly higher copolymer concentrations up to 90 wt %. Interestingly, the effective copolymer molecular nature was also observed in the ability to design various ordered mesophase geometries in large domain sizes. Our findings here show evidence that the synthetic strategy provides realistic control over a wide range of mesostructured phase geometries and their extended long-range ordering in the final replicas of the silica monolith frameworks. In addition, the HOM silica monoliths exhibited considerable structural stability against higher thermal temperature (up to 1000 degrees C) and longer hydrothermal treatment times under boiling water and steam. The remarkable structural findings of 3D frameworks, transparent monoliths, and micropores combined with large cage- and cylindrical-like mesopores are expected to find promising uses in materials chemistry.

Synthesis of ultrathin mesoporous NiCo2O4 nanosheets on carbon fiber paper as integrated high-performance electrodes for supercapacitors

NASA Astrophysics Data System (ADS)

Deng, Fangze; Yu, Lin; Cheng, Gao; Lin, Ting; Sun, Ming; Ye, Fei; Li, Yongfeng

2014-04-01

Two-dimensional ultrathin mesoporous NiCo2O4 nanosheets on carbon fiber paper (CFP) are synthesized through a facile solvothermal method combined with a post thermal treatment. The well interconnected ultrathin NiCo2O4 nanosheets directly grown on the carbon nanofibers could allow for easy diffusion of the electrolyte, shorten the transport path of ion and electron and accommodate the strain during cycling. As a result, superior pseudocapacitive performance is achieved with large specific capacitance of 999 F g-1 at a high current density of 20 A g-1. The capacitance loss is 15.6% after 3000 cycles at a current density of 10 A g-1, displaying good cycle ability and high rate capability.

Open-cage Fullerene-like Graphitic Carbons as Catalysts for Oxidative Dehydrogenation of Isobutane

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

Liang, Chengdu; Xie, Hong; Schwartz, Viviane

We report herein a facile synthesis of fullerene-like cages, which can be opened and closed through simple thermal treatments. A glassy carbon with enclosed fullerene-like cages of 2-3 nm was synthesized through a soft-template approach that created open mesopores of 7 nm. The open mesopores provided access to the fullerene-like cages, which were opened and closed through heat treatments in air and inert gas at various temperatures. Catalytic measurements showed that the open cages displayed strikingly higher activity for the oxidative dehydrogenation of isobutane in comparison to the close ones. We anticipate that this synthesis approach could unravel an avenuemore » for pursuing fundamental understanding of the unique catalytic properties of graphitic carbon nanostructures.« less

Pathways to Mesoporous Resin/Carbon Thin Films with Alternating Gyroid Morphology

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

Zhang, Qi; Matsuoka, Fumiaki; Suh, Hyo Seon

Three-dimensional (3D) mesoporous thin films with sub-100 nm periodic lattices are of increasing interest as templates for a number of nanotechnology applications, yet are hard to achieve with conventional top-down fabrication methods. Block copolymer self-assembly derived mesoscale structures provide a toolbox for such 3D template formation. In this work, single (alternating) gyroidal and double gyroidal mesoporous thin-film structures are achieved via solvent vapor annealing assisted co-assembly of poly(isoprene-block-styrene-block-ethylene oxide) (PI-b-PS-b-PEO, ISO) and resorcinol/phenol formaldehyde resols. In particular, the alternating gyroid thin-film morphology is highly desirable for potential template backfilling processes as a result of the large pore volume fraction. Inmore » situ grazing-incidence small-angle X-ray scattering during solvent annealing is employed as a tool to elucidate and navigate the pathway complexity of the structure formation processes. The resulting network structures are resistant to high temperatures provided an inert atmosphere. The thin films have tunable hydrophilicity from pyrolysis at different temperatures, while pore sizes can be tailored by varying ISO molar mass. A transfer technique between substrates is demonstrated for alternating gyroidal mesoporous thin films, circumventing the need to re-optimize film formation protocols for different substrates. Increased conductivity after pyrolysis at high temperatures demonstrates that these gyroidal mesoporous resin/carbon thin films have potential as functional 3D templates for a number of nanomaterials applications.« less

Study on physicochemical properties of functionalized-MWNTs with 3-aminopropyltriethoxysilane loaded TiO2 nanoparticles

NASA Astrophysics Data System (ADS)

Ahmad, Amirah; Razali, Mohd Hasmizam; Amin, Khairul Anuar Mat

2017-09-01

One of the exciting developments in science today is the design and synthesis of carbon nanotubes (CNTs) that possess novel properties and not exhibited by other individual organic and inorganic materials. CNTs are prepared using a chemical vapor deposition method with acetylene and synthesized mesoporous Ni-MCM41 as the carbon source and catalyst, respectively, and are then functionalized using 3-aminopropyltriethoxysilane (APTES) through the co-condensation method and loaded with commercial TiO2. Mesoporous Ni-MCM41 catalyst is first synthesized by hydrothermal method using sodium metasilicate as silica source and cetyltrimethylammonium bromide (CTABr) as a template. Results of Raman spectroscopy confirm that the synthesized carbon nanotubes are multi-walled. The type IV nitrogen adsorption-desorption isotherm and narrow pore size distribution proved that the functionalized-MWNTs loaded TiO2 is in mesopore range. Field Emission Scanning Electron Microscopy reveals that good dispersions of TiO2 nanoparticles onto functionalized-MWNTs with hair-like structure in between 3-8 nm. BET results indicate that functionalized-MWNTs loaded TiO2 possessed high surface area thus has considerable potential as an adsorbent and photocatalyst in environmental applications.

One-Pot Soft-Template Synthesis of Nanostructured Copper-Supported Mesoporous Carbon FDU-15 Electrocatalysts for Efficient CO2 Reduction.

PubMed

Şahin, Nihat Ege; Comminges, Clément; Le Valant, Anthony; Kiener, Julien; Parmentier, Julien; Napporn, Teko W; Melinte, Georgian; Ersen, Ovidiu; Kokoh, Kouakou B

2018-03-14

Copper-supported mesoporous carbon nanocatalysts (Cu/FDU-15) were synthesized using an easy and convenient one-pot soft-template method for low-overvoltage CO 2 electroreduction. TEM imaging revealed the presence of large Cu nanoparticles (diameter 140 nm) with Cu 2 O nanoparticles (16 nm) as an additional phase. From the electron tomography observations, we found that the copper particles were placed inside and on the exterior surface of the porous FDU-15 support, providing an accessible surface for electrocatalytic reactions. CO 2 electrolyses showed that the mesostructured Cu/FDU-15-350 cathode materials were active towards CO 2 conversion to formic acid with 22 % Faradaic efficiency at a remarkably low overpotential of 290 mV, hydrogen being the only side-product. The catalyst's activity correlates to the calculated metallic surface area, as determined from a geometrical model, confirming that the mesoporous channels act as a diffusion path for the CO 2 molecule, and that the whole Cu surface is accessible to CO 2 , even if particles are entrapped in the carbon matrix. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

PubMed Central

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

2013-01-01

We demonstrate a sustainable and efficient approach to produce high performance sulfur/carbon composite cathodes via a bottom-up catalytic approach. The selective oxidation of H2S by a nitrogen-enriched mesoporous carbon catalyst can produce elemental sulfur as a by-product which in-situ deposit onto the carbon framework. Due to the metal-free catalytic characteristic and high catalytic selectivity, the resulting sulfur/carbon composites have almost no impurities that thus can be used as cathode materials with compromising battery performance. The layer-by-layer sulfur deposition allows atomic sulfur binding strongly with carbon framework, providing efficient immobilization of sulfur. The nitrogen atoms doped on the carbon framework can increase the surface interactions with polysulfides, leading to the improvement in the trapping of polysulfides. Thus, the composites exhibit a reversible capacity of 939 mAh g−1 after 100 cycles at 0.2 C and an excellent rate capability of 527 mAh g−1 at 5 C after 70 cycles. PMID:24084754

A new family of fluidic precursors for the self-templated synthesis of hierarchical nanoporous carbons

DOE PAGES

Fulvio, Pasquale F.; Hillesheim, Patrick C.; Oyola, Yatsandra; ...

2016-06-24

Hierarchical nanoporous nitrogen-doped carbons were prepared from task specific ionic liquids having a bis-imidazolium motif linked with various organic groups. While ethyl chains linking the imidazolium ions afford microporous-mesoporous carbons, long or aromatic groups resulted in microporous samples.

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

PubMed Central

Ciraldo, Francesca E.; Goldmann, Wolfgang H.

2018-01-01

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

High-response and low-temperature nitrogen dioxide gas sensor based on gold-loaded mesoporous indium trioxide.

PubMed

Li, Shan; Cheng, Ming; Liu, Guannan; Zhao, Lianjing; Zhang, Bo; Gao, Yuan; Lu, Huiying; Wang, Haiyu; Zhao, Jing; Liu, Fangmeng; Yan, Xu; Zhang, Tong; Lu, Geyu

2018-04-10

Nitrogen dioxide (NO 2 ), as a typical threatening atmospheric pollutant, is hazardous to the environment and human health. Thus, the development of a gas sensor with high response and low detection limit for NO 2 detection is highly important. The highly ordered mesoporous indium trioxide (In 2 O 3 ) prepared by simple nanocasting method using mesoporous silica as template and decorated with Au nanoparticles was investigated for NO 2 detection. The prepared materials were characterized by X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy. Characterization results showed that the samples exhibited ordered mesostructure and were successfully decorated with Au. The gas sensing performance of the sensors based on a series of Au-loaded mesoporous In 2 O 3 were systematically investigated. The Au loading level strongly affected the sensing performance toward NO 2 . The optimal sensor, which was based on 0.5 wt% Au-loaded In 2 O 3 , displayed high sensor response and low detection limit of 10 ppb at low operating temperature of 65 °C. The excellent sensing properties were mainly attributed to the ordered mesoporous structure and the catalytic performance of Au. We believe that the Au-loaded mesoporous In 2 O 3 can provide a promising platform for NO 2 gas sensors with excellent performance. Copyright © 2018 Elsevier Inc. All rights reserved.

Mesopore quality determines the lifetime of hierarchically structured zeolite catalysts

NASA Astrophysics Data System (ADS)

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

2014-05-01

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

Particulate inverse opal carbon electrodes for lithium-ion batteries.

PubMed

Kang, Da-Young; Kim, Sang-Ok; Chae, Yu Jin; Lee, Joong Kee; Moon, Jun Hyuk

2013-01-29

Inverse opal carbon materials were used as anodes for lithium ion batteries. We applied particulate inverse opal structures and their dispersion in the formation of anode electrodes via solution casting. We prepared aminophenyl-grafted inverse opal carbons (a-IOC), inverse opal carbons with mesopores (mIOC), and bare inverse opal carbons (IOC) and investigated the electrochemical behavior of these samples as anode materials. Surface modification by aminophenyl groups was confirmed by XPS measurements. TEM images showed mesopores, and the specific area of mIOC was compared with that of IOC using BET analysis. A half-cell test was performed to compare a-IOC with IOC and mIOC with IOC. In the case of the a-IOC structure, the cell test revealed no improvement in the reversible specific capacity or the cycle performance. The mIOC cell showed a reversible specific capacity of 432 mAh/g, and the capacity was maintained at 88%-approximately 380 mAh/g-over 20 cycles.

An Efficient and Reusable Embedded Ru Catalyst for the Hydrogenolysis of Levulinic Acid to γ-Valerolactone.

PubMed

Wei, Zuojun; Lou, Jiongtao; Su, Chuanmin; Guo, Dechao; Liu, Yingxin; Deng, Shuguang

2017-04-22

To achieve a higher activity and reusability of a Ru-based catalyst, Ru nanoparticles were embedded in N-doped mesoporous carbon through a hard-template method. The catalyst showed excellent catalytic performance (314 h -1 turnover frequency) and recyclability (reusable five times with 3 % activity loss) for the hydrogenolysis of levulinic acid to γ-valerolactone. Compared with the mesoporous carbon without N-doping and conventional activated carbon, the introduction of N-dopant effectively improved the dispersion of Ru nanoparticles, decreased the average size of Ru nanoparticles to as small as 1.32 nm, and improved the adsorption of levulinic acid, which contributed to the increase in the activity of the catalyst. Additionally, the embedding method increased the interaction between Ru nanoparticles and carbon support in contrast with the conventional impregnation method, thus preventing the Ru nanoparticles from migration, aggregation, and leaching from the carbon surface and therefore increasing the reusability of the catalyst. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

PubMed

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

2013-03-01

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

A molecularly imprinted dual-emission carbon dot-quantum dot mesoporous hybrid for ratiometric determination of anti-inflammatory drug celecoxib

NASA Astrophysics Data System (ADS)

Amjadi, Mohammad; Jalili, Roghayeh

2018-02-01

We report on a ratiometric fluorescent sensor based on dual-emission molecularly imprinted mesoporous silica embedded with carbon dots and CdTe quantum dots (mMIP@CDs/QDs) for celecoxib (CLX) as target molecule. The fluorescence of the embedded CDs is insensitive to the analyte while the green emissive QDs are selectively quenched by it. This effect is much stronger for the MIP than for the non-imprinted polymer, which indicates a good recognition ability of the mesoporous MIP. The hybrid sensor also exhibited good selectivity to CLX over other substances. The ratio of the intensity at two wavelengths (F550/F440) proportionally decreased with the increasing of CLX concentration in the range of 0.08-0.90 μM. A detection limit as low as 57 nM was achieved. Experimental results testified that this sensor was highly sensitive and selective for the detection of CLX in human serum samples.

Separator Decoration with Cobalt/Nitrogen Codoped Carbon for Highly Efficient Polysulfide Confinement in Lithium-Sulfur Batteries.

PubMed

Hu, Wen; Hirota, Yuichiro; Zhu, Yexin; Yoshida, Nao; Miyamoto, Manabu; Zheng, Tao; Nishiyama, Norikazu

2017-09-22

A macro-/mesoporous Co-N-C-decorated separator is proposed to confine and reutilize migrating polysulfides. Endowed with a desirable structure and synchronous lithio- and sulfiphilic chemistry, the macro-/mesoporous Co-N-C interface manipulates large polysulfide adsorption uptake, enabling good polysulfide adsorption kinetics, reversible electrocatalysis toward redox of anchored polysulfides, and facile charge transport. It significantly boosts the performance of a simple 70 wt % S/MWCNTs (MWCNTs=multi-walled carbon nanotubes) cathode, achieving high initial capacities (e.g., 1406 mAh g -1 at 0.2C, 1203 mAh g -1 at 1C), nearly 100 % Coulombic efficiencies, and high reversible capacities after cycle tests (e.g., 828.4 mAh g -1 at 1C after 100 cycles) at both low and high current rates. These results demonstrate that decorating separator with macro-/mesoporous Co-N-C paves a feasible way for developing advanced Li-S batteries. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Sample Desorption/Onization From Mesoporous Silica

DOEpatents

Iyer, Srinivas; Dattelbaum, Andrew M.

2005-10-25

Mesoporous silica is shown to be a sample holder for laser desorption/ionization of mass spectrometry. Supported mesoporous silica was prepared by coating an ethanolic silicate solution having a removable surfactant onto a substrate to produce a self-assembled, ordered, nanocomposite silica thin film. The surfactant was chosen to provide a desired pore size between about 1 nanometer diameter and 50 nanometers diameter. Removal of the surfactant resulted in a mesoporous silica thin film on the substrate. Samples having a molecular weight below 1000, such as C.sub.60 and tryptophan, were adsorbed onto and into the mesoporous silica thin film sample holder and analyzed using laser desorption/ionization mass spectrometry.

Electrospinning-based synthesis of highly ordered mesoporous silica fiber for lab-in-syringe enrichment of plasma peptides.

PubMed

Zhu, Gang-Tian; Li, Xiao-Shui; Fu, Xiao-Meng; Wu, Jian-Yuan; Yuan, Bi-Feng; Feng, Yu-Qi

2012-10-14

Silica fiber with highly ordered mesoporous structure and continuously long fibrous property was synthesized on a large-scale for the first time. It can be applied to the rapid (less than 3 min) and effective enrichment of endogenous peptides with a novel lab-in-syringe approach.

Development of amperometric glucose biosensor through immobilizing enzyme in a Pt nanoparticles/mesoporous carbon matrix.

PubMed

Yu, Jingjing; Yu, Donglei; Zhao, Tian; Zeng, Baizhao

2008-02-15

Pt nanoparticles were deposited on mesoporous carbon material CMK-3. Glucose oxidase (GOx) was immobilized in the resulting Pt nanoparticles/mesoporous carbon (Pt/CMK-3) matrix, and then the mixture was cast on a glassy carbon electrode (GCE) using gelatin as a binder. The glucose biosensor exhibited excellent current response to glucose after cross-linking with glutaraldehyde. At 0.6V (vs. SCE) the response current was linear to glucose concentration in the range of 0.04-12.2mM. The response time (time for achieving 95% of the maximum current) was 15s and the detection limit (S/N=3) was 1 microM. The Michaelis-Menten constant (K(m)(app)) and the maximum current density (i(max)) were 10.8 mM and 908 microAcm(-2), respectively. The activation energy of the enzymatic reaction was estimated to be 22.54 kJ mol(-1). The biosensor showed good stability. It achieved the maximum response current at about 52 degrees C and retained 95.1% of its initial response current after being stored for 30 days. In addition, some fabrication and operation parameters for the biosensor were optimized in this work. The biosensor was used to monitor the glucose levels of serum samples after being covered with an extra Nafion film to improve its anti-interferent ability and satisfied results were obtained.

A mesoporous carbon–sulfur composite as cathode material for high rate lithium sulfur batteries

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

Choi, Hyunji; Zhao, Xiaohui; Kim, Dul-Sun

2014-10-15

Highlights: • CMK-3 mesoporous carbon was synthesized as conducting reservoir for housing sulfur. • Sulfur/CMK-3 composites were prepared by two-stage thermal treatment. • The composite at 300 °C for 20 h shows improved electrochemical properties. - Abstract: Sulfur composite was prepared by encapsulating sulfur into CMK-3 mesoporous carbon with different heating times and then used as the cathode material for lithium sulfur batteries. Thermal treatment at 300 °C plays an important role in the sulfur encapsulation process. With 20 h of heating time, a portion of sulfur remained on the surface of carbon, whereas with 60 h of heating time,more » sulfur is confined deeply in the small pores of carbon that cannot be fully exploited in the redox reaction, thus causing low capacity. The S/CMK-3 composite with thermal treatment for 40 h at 300 °C contained 51.3 wt.% sulfur and delivered a high initial capacity of 1375 mA h g{sup −1} at 0.1 C. Moreover, it showed good capacity retention of 704 mA h g{sup −1} at 0.1 C and 578 mA h g{sup −1} at 2 C even after 100 cycles, which proves its potential as a cathode material for high capability lithium sulfur batteries.« less

Diagnosis of EGFR exon21 L858R point mutation as lung cancer biomarker by electrochemical DNA biosensor based on reduced graphene oxide /functionalized ordered mesoporous carbon/Ni-oxytetracycline metallopolymer nanoparticles modified pencil graphite electrode.

PubMed

Shoja, Yalda; Kermanpur, Ahmad; Karimzadeh, Fathallah

2018-08-15

In this present work we made a novel, fast, selective and sensitive electrochemical genobiosensor to detection of EGFR exon 21 point mutation based on two step electropolymerization of Ni(II)-oxytetracycline conducting metallopolymer nanoparticles (Ni-OTC NPs) on the surface of pencil graphite electrode (PGE) which was modified by reduced graphene oxide/carboxyl functionalized ordered mesoporous carbon (rGO/f-OMC) nanocomposite. ssDNA capture probe with amine groups at the5' end which applied as recognition element was immobilized on the rGO/f-OMC/PGE surface via the strong amide bond. Ni-OTC metallopolymer NPs were electropolymerized to rGO/ssDNA-OMC/PGE surface and then hybridization fallows through the peak current change in differential pulse voltammetry (DPV) using Ni-OTC NPs as a redox label. The biosensor was characterized by field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), FT-IR spectroscopy, energy dispersive X-ray spectroscopy (EDX), cyclic voltammetry and Nitrogen adsorption-desorption analysis. The Ni-OTC current response verified only the complementary sequence indicating a significant reduction current signal in comparison to single point mismatched and non-complementary and sequences. Under optimal conditions, the prepared biosensor showed long-term stability (21 days) with a wide linear range from 0.1 µM to 3 µM with high sensitivity (0.0188 mA/µM) and low detection limit (120 nM). Copyright © 2018 Elsevier B.V. All rights reserved.

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

PubMed

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

2014-01-21

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

Mesoporous mixed metal oxides derived from P123-templated Mg-Al layered double hydroxides

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

Wang Jun, E-mail: zhqw1888@sohu.co; College of Chemical Engineering, Harbin Institute of Technology, Harbin 150001; Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, 150001

2010-11-15

We report the preparation of mesoporous mixed metal oxides (MMOs) through a soft template method. Different amounts of P123 were used as structure directing agent to synthesize P123-templated Mg-Al layered double hydroxides (LDHs). After calcination of as-synthesized LDHs at 500 {sup o}C, the ordered mesopores were obtained by removal of P123. The mesoporous Mg-Al MMOs fabricated by using 2 wt% P123 exhibited a high specific surface area of 108.1 m{sup 2}/g, and wide distribution of pore size (2-18 nm). An investigation of the 'memory effect' of the mesoporous MMOs revealed that they were successfully reconstructed to ibuprofen intercalated LDHs havingmore » different gallery heights, which indicated different intercalation capacities. Due to their mesoporosity these unique MMOs have particular potential as drug or catalyst carriers. - Graphical abstract: Ordered mesoporous Mg-Al MMOs can be obtained through the calcination of P123-templated Mg-Al-CO{sub 3} LDHs. The pore diameter is 2.2 nm. At the presence of ibuprofen, the Mg-Al MMOs can recover to Mg-Al-IBU LDHs, based on its 'remember effect'. Display Omitted« less

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

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

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

2009-11-15

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

Ordered Mesoporous NiCeAl Containing Catalysts for Hydrogenolysis of Sorbitol to Glycols

NASA Astrophysics Data System (ADS)

Zhou, Zhiwei; Zhang, Jiaqi; Qin, Juan; Li, Dong; Wu, Wenliang

2018-03-01

Cellulose-derived sorbitol is emerging as a feasible and renewable feedstock for the production of value-added chemicals. Highly active and stable catalyst is essential for sorbitol hydrogenolysis. Ordered mesoporous M- xNi yCeAl catalysts with different loadings of nickel and cerium species were successfully synthesized via one-pot evaporation-induced self-assembly strategy (EISA) and their catalytic performance were tested in the hydrogenolysis of sorbitol. The physical chemical properties for the catalysts were characterized by XRD, N2 physisorption, H2-TPR, H2 impulse chemisorption, ICP and TEM techniques. The results showed that the ordered mesopores with uniform pore sizes can be obtained and the Ni nanoparticles around 6 nm in size were homogeneously dispersed in the mesopore channels. A little amount of cerium species introduced would be beneficial to their textural properties resulting in higher Ni dispersion, metal area and smaller size of Ni nanoparticles. The M-10Ni2CeAl catalyst with Ni and Ce loading of 10.9 and 6.3 wt % shows better catalytic performance than other catalysts, and the yield of 1,2-PG and EG can reach 56.9% at 493 K and 6 MPa pressure for 8 h after repeating reactions for 12 times without obvious deterioration of physical and chemical properties. Ordered mesoporous M-NiCeAl catalysts are active and stable in sorbitol hydrogenolysis.

Preparation of Bamboo Chars and Bamboo Activated Carbons to Remove Color and COD from Ink Wastewater.

PubMed

Hata, Motohide; Amano, Yoshimasa; Thiravetyan, Paitip; Machida, Motoi

2016-01-01

Bamboo chars and bamboo activated carbons prepared by steam activation were applied for ink wastewater treatment. Bamboo char at 800 °C was the best for the removal of color and chemical oxygen demand (COD) from ink wastewater compared to bamboo chars at 300 to 700 °C due to higher surface area and mesopore volume. Bamboo activated carbon at 600 °C (S600) was the best compared to bamboo activated carbon at 800 °C (S800), although S800 had larger surface area (1108 m(2)/g) than S600 (734 m(2)/g). S600 had higher mesopore volume (0.20 cm(3)/g) than S800 (0.16 cm(3)/g) and therefore achieved higher color and COD removal. All bamboo activated carbons showed higher color and COD removal efficiency than commercial activated carbon. In addition, S600 had the superior adsorption capacity for methylene blue (0.89 mmol/g). Therefore, bamboo is a suitable material to prepare adsorbents for removal of organic pollutants.

Variations in pore characteristics in high volatile bituminous coals: Implications for coal bed gas content

USGS Publications Warehouse

Mastalerz, Maria; Drobniak, A.; Strapoc, D.; Solano-Acosta, W.; Rupp, J.

2008-01-01

The Seelyville Coal Member of the Linton Formation (Pennsylvanian) in Indiana was studied to: 1) understand variations in pore characteristics within a coal seam at a single location and compare these variations with changes occurring between the same coal at different locations, 2) elaborate on the influence of mineral-matter and maceral composition on mesopore and micropore characteristics, and 3) discuss implications of these variations for coal bed gas content. The coal is high volatile bituminous rank with R0 ranging from 0.57% to 0.60%. BET specific surface areas (determined by nitrogen adsorption) of the coals samples studied range from 1.8 to 22.9??m2/g, BJH adsorption mesopore volumes from 0.0041 to 0.0339??cm3/g, and micropore volumes (determined by carbon dioxide adsorption) from 0.0315 to 0.0540??cm3/g. The coals that had the largest specific surface areas and largest mesopore volumes occur at the shallowest depths, whereas the smallest values for these two parameters occur in the deepest coals. Micropore volumes, in contrast, are not depth-dependent. In the coal samples examined for this study, mineral-matter content influenced both specific surface area as well as mesopore and micropore volumes. It is especially clear in the case of micropores, where an increase in mineral-matter content parallels the decrease of micropore volume of the coal. No obvious relationships were observed between the total vitrinite content and pore characteristics but, after splitting vitrinite into individual macerals, we see that collotelinite influences both meso- and micropore volume positively, whereas collodetrinite contributes to the reduction of mesopore and micropore volumes. There are large variations in gas content within a single coal at a single location. Because of this variability, the entire thickness of the coal must be desorbed in order to determine gas content reliably and to accurately calculate the level of gas saturation. ?? 2008 Elsevier B.V. All rights reserved.

Hierarchical porous carbons with layer-by-layer motif architectures from confined soft-template self-assembly in layered materials

NASA Astrophysics Data System (ADS)

Wang, Jie; Tang, Jing; Ding, Bing; Malgras, Victor; Chang, Zhi; Hao, Xiaodong; Wang, Ya; Dou, Hui; Zhang, Xiaogang; Yamauchi, Yusuke

2017-06-01

Although various two-dimensional (2D) nanomaterials have been explored as promising capacitive materials due to their unique layered structure, their natural restacking tendency impedes electrolyte transport and significantly restricts their practical applications. Herein, we synthesize all-carbon layer-by-layer motif architectures by introducing 2D ordered mesoporous carbons (OMC) within the interlayer space of 2D nanomaterials. As a proof of concept, MXenes are selected as 2D hosts to design 2D-2D heterostructures. Further removing the metal elements from MXenes leads to the formation of all-carbon 2D-2D heterostructures consisting of alternating layers of MXene-derived carbon (MDC) and OMC. The OMC layers intercalated with the MDC layers not only prevent restacking but also facilitate ion diffusion and electron transfer. The performance of the obtained hybrid carbons as supercapacitor electrodes demonstrates their potential for upcoming electronic devices. This method allows to overcome the restacking and blocking of 2D nanomaterials by constructing ion-accessible OMC within the 2D host material.

A New Porous Hybrid Material Derived From Silica Fume and Alginate for Sustainable Pollutants Reduction.

PubMed

Zanoletti, Alessandra; Vassura, Ivano; Venturini, Elisa; Monai, Matteo; Montini, Tiziano; Federici, Stefania; Zacco, Annalisa; Treccani, Laura; Bontempi, Elza

2018-01-01

In this work a new mesoporous adsorbent material obtained from a natural, high abundant raw material and a high volume industrial by-product is presented. The material is consolidated by the gelling properties of alginate and by decomposition of sodium-bicarbonate controlled porosity at low temperatures (70-80°C) at different scale lengths. The structural, thermal, and morphological characterization shows that the material is a mesoporous organic-inorganic hybrid. The material is tested as adsorbent, showing high performances. Methylene blue, used as model pollutant, can be adsorbed and removed from aqueous solutions even at a high concentration with efficiency up to 94%. By coating the material with a 100 nm thin film of titania, good photodegradation performance (more than 20%) can be imparted. Based on embodied energy and carbon footprint of its primary production, the sustainability of the new obtained material is evaluated and quantified in respect to activated carbon as well. It is shown that the new proposed material has an embodied energy lower than one order of magnitude in respect to the one of activated carbon, which represents the gold standards. The versatility of the new material is also demonstrated in terms of its design and manufacturing possibilities In addition, this material can be printed in 3D. Finally, preliminary results about its ability to capture diesel exhaust particulate matter are reported. The sample exposed to diesel contains a large amount of carbon in its surface. At the best of our knowledge, this is the first time that hybrid porous materials are proposed as a new class of sustainable materials, produced to reduce pollutants in the wastewaters and in the atmosphere.

A new porous hybrid material derived from silica fume and alginate for sustainable pollutants reduction

NASA Astrophysics Data System (ADS)

Zanoletti, Alessandra; Vassura, Ivano; Venturini, Elisa; Monai, Matteo; Montini, Tiziano; Federici, Stefania; Zacco, Annalisa; Treccani, Laura; Bontempi, Elza

2018-03-01

In this work a new mesoporous adsorbent material obtained from a natural, high abundant raw material and a high volume industrial by-product is presented. The material is consolidated by the gelling properties of alginate and by decomposition of sodium-bicarbonate controlled porosity at low temperatures (70-80°C) at different scale lengths. The structural, thermal, and morphological characterization shows that the material is a mesoporous organic-inorganic hybrid. The material is tested as adsorbent, showing high performances. Methylene blue, used as model pollutant, can be adsorbed and removed from aqueous solutions even at a high concentration with efficiency up to 94%. By coating the material with a 100 nm thin film of titania, good photodegradation performance (more than 20%) can be imparted. Based on embodied energy and carbon footprint of its primary production, the sustainability of the new obtained material is evaluated and quantified in respect to activated carbon as well. It is shown that the new proposed material has an embodied energy lower than one order of magnitude in respect to the one of activated carbon, which represents the gold standards. The versatility of the new material is also demonstrated in terms of its design and manufacturing possibilities. In addition, this material can be printed in 3D. Finally, preliminary results about its ability to capture diesel exhaust particulate matter are reported. The sample exposed to diesel contains a large amount of carbon in its surface. At the best of our knowledge this is the first time that hybrid porous materials are proposed as a new class of sustainable materials, produced to reduce pollutants in the wastewaters and in the atmosphere.

A New Porous Hybrid Material Derived From Silica Fume and Alginate for Sustainable Pollutants Reduction

PubMed Central

Zanoletti, Alessandra; Vassura, Ivano; Venturini, Elisa; Monai, Matteo; Montini, Tiziano; Federici, Stefania; Zacco, Annalisa; Treccani, Laura; Bontempi, Elza

2018-01-01

In this work a new mesoporous adsorbent material obtained from a natural, high abundant raw material and a high volume industrial by-product is presented. The material is consolidated by the gelling properties of alginate and by decomposition of sodium-bicarbonate controlled porosity at low temperatures (70–80°C) at different scale lengths. The structural, thermal, and morphological characterization shows that the material is a mesoporous organic-inorganic hybrid. The material is tested as adsorbent, showing high performances. Methylene blue, used as model pollutant, can be adsorbed and removed from aqueous solutions even at a high concentration with efficiency up to 94%. By coating the material with a 100 nm thin film of titania, good photodegradation performance (more than 20%) can be imparted. Based on embodied energy and carbon footprint of its primary production, the sustainability of the new obtained material is evaluated and quantified in respect to activated carbon as well. It is shown that the new proposed material has an embodied energy lower than one order of magnitude in respect to the one of activated carbon, which represents the gold standards. The versatility of the new material is also demonstrated in terms of its design and manufacturing possibilities In addition, this material can be printed in 3D. Finally, preliminary results about its ability to capture diesel exhaust particulate matter are reported. The sample exposed to diesel contains a large amount of carbon in its surface. At the best of our knowledge, this is the first time that hybrid porous materials are proposed as a new class of sustainable materials, produced to reduce pollutants in the wastewaters and in the atmosphere. PMID:29616212

Evaluation of heavy crude oil from a water-oil model system as starting material for the preparation of adsorbents type NaY zeolite-templated carbon.

PubMed

Elles-Pérez, Cindy J; Muñoz-Acevedo, Amner; Guzmán, Andrés; Camargo, Hernando; Henao, José

2017-07-01

In this work, NaY zeolite is explored as a possible "template" to obtain porous materials type ZTC from the adsorption of heavy crude oil in a water-oil model system (emulsion). In order to produce the adsorbents, a cationic surfactant is selected to facilitate the adsorption of the crude oil into the pores of the zeolite and to get the composite, which was activated with controlled thermal treatments (T: 700-800 °C and t: 0.5-1 h) in inert conditions (N 2 gaseous). The starting materials, composite and porous carbons were characterized using structural/surface analysis techniques (API Gravity, SARA, IR, XRD, XRF, TGA, Langmuir isotherms, BET and SEM). The results showed that four types of mesoporous carbons were produced with specific surface areas between 70 ± 1 m 2 /g and 220 ± 3 m 2 /g, average pore volumes between 0.144 cm 3 /g and 0.40 cm 3 /g and average pore widths between 4.9 nm and 8.3 nm. The activation conditions of 800 °C and 1 h allowed to make the carbonaceous material with the best surface characteristics (220 ± 3 m 2 /g, 0.27 cm 3 /g, and 4.9 nm). Therefore, it is concluded that under assay conditions employed, the heavy crude oil, as a mixed model (water-oil), from an aqueous environment is a starting material suitable for preparation of "mesoporous" carbons. Copyright © 2017 Elsevier Ltd. All rights reserved.

Mesoporous NiCo2O4 nano-needles supported by 3D interconnected carbon network on Ni foam for electrochemical energy storage

NASA Astrophysics Data System (ADS)

Lu, Congxiang; Liu, Wen-wen; Pan, Hui; Tay, Beng Kang; Wang, Xingli; Liang, Kun; Wei, Xuezhe

2018-05-01

In this work, a three dimensional (3D) interconnected carbon network consisting of ultrathin graphite (UG) and carbon nanotubes (CNTs) on Ni foam is fabricated and employed as a novel type of substrate for mesoporous NiCo2O4 nano-needles. The successfully synthesized NiCo2O4 nano-needles/CNTs/UG on Ni foam has many advantages including facile electrolyte access and direct conducting pathways towards current collectors, which enable it to be a promising electrode material in battery-like electrochemical energy storage. Encouragingly, a high capacity of 135.1 mAh/g at the current density of 1 A/g, superior rate performance and also stable cycling for 1200 cycles at the current density of 5 A/g have been demonstrated in this novel material.

Mesoporous Phosphorus-Doped g-C3N4 Nanostructured Flowers with Superior Photocatalytic Hydrogen Evolution Performance.

PubMed

Zhu, Yun-Pei; Ren, Tie-Zhen; Yuan, Zhong-Yong

2015-08-05

Graphitic carbon nitride (g-C3N4) has been deemed a promising heterogeneous metal-free catalyst for a wide range of applications, such as solar energy utilization toward water splitting, and its photocatalytic performance is reasonably adjustable through tailoring its texture and its electronic and optical properties. Here phosphorus-doped graphitic carbon nitride nanostructured flowers of in-plane mesopores are synthesized by a co-condensation method in the absence of any templates. The interesting structures, together with the phosphorus doping, can promote light trapping, mass transfer, and charge separation, enabling it to perform as a more impressive catalyst than its pristine carbon nitride counterpart for catalytic hydrogen evolution under visible light irradiation. The catalyst has low cost, is environmentally friendly, and represents a potential candidate in photoelectrochemistry.

Potential of ordered mesoporous silica for oral delivery of poorly soluble drugs.

PubMed

Vialpando, Monica; Martens, Johan A; Van den Mooter, Guy

2011-08-01

The use of ordered mesoporous silica is one of the more recent and rapidly developing formulation techniques for enhancing the solubility of poorly water-soluble drugs. Their large surface area and pore volume make ordered mesoporous silica materials excellent candidates for efficient drug loading and rapid release. While this new approach offers many promising advantages, further research is still necessary to elucidate the molecular mechanisms and to improve our scientific insight into the behavior of this system. In this review, the significant developments to date are presented and research challenges highlighted. Aspects of downstream processability are discussed in view of their special bulk powder properties and unique pore architecture. Lastly, perspectives for successful oral dosage form development are presented.

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

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

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

2011-09-15

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

A high performance flexible all solid state supercapacitor based on the MnO2 sphere coated macro/mesoporous Ni/C electrode and ionic conducting electrolyte

NASA Astrophysics Data System (ADS)

Zhi, Jian; Reiser, Oliver; Wang, Youfu; Hu, Aiguo

2016-06-01

A high contact resistance between the active materials and the current collector, a low ionic conductivity of the gel electrolyte, and an impenetrable electrode structure are the three major barriers which greatly limit the capacitance of MnO2 in solid state supercapacitors. As a potential solution to these problems, in this work we report a novel electrode for solid state supercapacitors, based on a ternary system composed of hierarchical MnO2 spheres as the active material, macroporous Ni foam as gel penetrable skeletons and an ordered mesoporous carbon (OMC) membrane as the charge-transport accelerating layer. By employing butyl-3-methylimidazolium chloride (BMIMCl) modified gels as the ionic conducting electrolyte, the utilization efficiency of MnO2 on the specific capacitance was enhanced up to 88% of the theoretical value, delivering a volumetric capacitance of 81 F cm-3, which is the highest value among MnO2 based solid state supercapacitors. Moreover, such a flexible device exhibits exceptional volumetric energy and power density (6.6 Wh L-1 and 549 W L-1, based on the whole device volume) combined with a small capacity loss of 8.5% after 6000 cycles under twisting. These encouraging findings unambiguously overcome the energy bottleneck of MnO2 in solid state supercapacitors, and open up a new application of macro/mesoporous materials in flexible devices.A high contact resistance between the active materials and the current collector, a low ionic conductivity of the gel electrolyte, and an impenetrable electrode structure are the three major barriers which greatly limit the capacitance of MnO2 in solid state supercapacitors. As a potential solution to these problems, in this work we report a novel electrode for solid state supercapacitors, based on a ternary system composed of hierarchical MnO2 spheres as the active material, macroporous Ni foam as gel penetrable skeletons and an ordered mesoporous carbon (OMC) membrane as the charge-transport accelerating layer. By employing butyl-3-methylimidazolium chloride (BMIMCl) modified gels as the ionic conducting electrolyte, the utilization efficiency of MnO2 on the specific capacitance was enhanced up to 88% of the theoretical value, delivering a volumetric capacitance of 81 F cm-3, which is the highest value among MnO2 based solid state supercapacitors. Moreover, such a flexible device exhibits exceptional volumetric energy and power density (6.6 Wh L-1 and 549 W L-1, based on the whole device volume) combined with a small capacity loss of 8.5% after 6000 cycles under twisting. These encouraging findings unambiguously overcome the energy bottleneck of MnO2 in solid state supercapacitors, and open up a new application of macro/mesoporous materials in flexible devices. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr02215d

Recent advances in functionalized micro and mesoporous carbon materials: synthesis and applications.

PubMed

Benzigar, Mercy R; Talapaneni, Siddulu Naidu; Joseph, Stalin; Ramadass, Kavitha; Singh, Gurwinder; Scaranto, Jessica; Ravon, Ugo; Al-Bahily, Khalid; Vinu, Ajayan

2018-04-23

Functionalized nanoporous carbon materials have attracted the colossal interest of the materials science fraternity owing to their intriguing physical and chemical properties including a well-ordered porous structure, exemplary high specific surface areas, electronic and ionic conductivity, excellent accessibility to active sites, and enhanced mass transport and diffusion. These properties make them a special and unique choice for various applications in divergent fields such as energy storage batteries, supercapacitors, energy conversion fuel cells, adsorption/separation of bulky molecules, heterogeneous catalysts, catalyst supports, photocatalysis, carbon capture, gas storage, biomolecule detection, vapour sensing and drug delivery. Because of the anisotropic and synergistic effects arising from the heteroatom doping at the nanoscale, these novel materials show high potential especially in electrochemical applications such as batteries, supercapacitors and electrocatalysts for fuel cell applications and water electrolysis. In order to gain the optimal benefit, it is necessary to implement tailor made functionalities in the porous carbon surfaces as well as in the carbon skeleton through the comprehensive experimentation. These most appealing nanoporous carbon materials can be synthesized through the carbonization of high carbon containing molecular precursors by using soft or hard templating or non-templating pathways. This review encompasses the approaches and the wide range of methodologies that have been employed over the last five years in the preparation and functionalisation of nanoporous carbon materials via incorporation of metals, non-metal heteroatoms, multiple heteroatoms, and various surface functional groups that mostly dictate their place in a wide range of practical applications.

Slat templated formation of efficient oxygen reduction electrocatalyst with a fluidic precursor

NASA Astrophysics Data System (ADS)

Tan, Yao

2018-05-01

Development of cost-effective and efficient oxygen reduction catalyst is critical for the commercialization of proton exchange membrane fuel cell. Metal and nitrogen co-doped carbon is recognized as a promising alternative to traditional platinum-based oxygen reduction catalyst. Herein, we report a novel metal and nitrogen co-doped carbon catalyst with an ionic liquid precursor. Salt template, which can be easily removed with mild treatment after the synthesis, is used to generate abundant mesopores in the resulting catalyst. We show that the novel catalyst shows a superior activity comparable to commercial Pt/C catalyst. Furthermore, the important role of the mesopore for the activity of the catalyst is demonstrated.

Formation of monodisperse mesoporous silica microparticles via spray-drying.

PubMed

Waldron, Kathryn; Wu, Winston Duo; Wu, Zhangxiong; Liu, Wenjie; Selomulya, Cordelia; Zhao, Dongyuan; Chen, Xiao Dong

2014-03-15

In this work, a protocol to synthesize monodisperse mesoporous silica microparticles via a unique microfluidic jet spray-drying route is reported for the first time. The microparticles demonstrated highly ordered hexagonal mesostructures with surface areas ranging from ~900 up to 1500 m(2)/g and pore volumes from ~0.6 to 0.8 cm(3)/g. The particle size could be easily controlled from ~50 to 100 μm from the same diameter nozzle via changing the initial solute content, or changing the drying temperature. The ratio of the surfactant (CTAB) and silica (TEOS), and the amount of water in the precursor were found to affect the degree of ordering of mesopores by promoting either the self-assembly of the surfactant-silica micelles or the condensation of the silica as two competing processes in evaporation induced self-assembly. The drying rate and the curvature of particles also affected the self-assembly of the mesostructure. The particle mesostructure is not influenced by the inlet drying temperature in the range of 92-160 °C, with even a relatively low temperature of 92 °C producing highly ordered mesoporous microparticles. The spray-drying derived mesoporous silica microparticles, while of larger sizes and more rapidly synthesized, showed a comparable performance with the conventional mesoporous silica MCM-41 in controlled release of a dye, Rhodamine B, indicating that these spray dried microparticles could be used for the immobilisation and controlled release of small molecules. Copyright © 2013 Elsevier Inc. All rights reserved.

Hierarchically Porous Graphitic Carbon with Simultaneously High Surface Area and Colossal Pore Volume Engineered via Ice Templating

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

Estevez, Luis; Prabhakaran, Venkateshkumar; Garcia, Adam L.

Developing hierarchical porous carbon (HPC) materials with competing textural characteristics such as surface area and pore volume in one material is difficult to accomplish—particulalry for an atomically ordered (graphitic) carbon. Herein we describe a synthesis strategy to engineer tunable hierarchically porous carbon (HPC) materials across micro- meso- and macroporous length scales, allowing the fabrication of a graphitic HPC with both very high surface area (> 2500 m2/g) and pore volume (>10 cm3/g), the combination of which has not been seen previously. The mesopore volume alone for these materials is up to 7.91 cm3/g, the highest ever reported. The unique materialmore » was explored for use as a supercapaictor electrode and for oil adsorption; two applications that require textural properties that are typicaly exclusive to one another. This design scheme for HPCs can be utilized in broad applications, including electrochemical systems such as batteries and supercapacitors, sorbents, and catalyst supports.« less

Hierarchical Mesoporous Zinc-Nickel-Cobalt Ternary Oxide Nanowire Arrays on Nickel Foam as High-Performance Electrodes for Supercapacitors.

PubMed

Wu, Chun; Cai, Junjie; Zhang, Qiaobao; Zhou, Xiang; Zhu, Ying; Shen, Pei Kang; Zhang, Kaili

2015-12-09

Nickel foam supported hierarchical mesoporous Zn-Ni-Co ternary oxide (ZNCO) nanowire arrays are synthesized by a simple two-step approach including a hydrothermal method and subsequent calcination process and directly utilized for supercapacitive investigation for the first time. The nickel foam supported hierarchical mesoporous ZNCO nanowire arrays possess an ultrahigh specific capacitance value of 2481.8 F g(-1) at 1 A g(-1) and excellent rate capability of about 91.9% capacitance retention at 5 A g(-1). More importantly, an asymmetric supercapacitor with a high energy density (35.6 Wh kg(-1)) and remarkable cycle stability performance (94% capacitance retention over 3000 cycles) is assembled successfully by employing the ZNCO electrode as positive electrode and activated carbon as negative electrode. The remarkable electrochemical behaviors demonstrate that the nickel foam supported hierarchical mesoporous ZNCO nanowire array electrodes are highly desirable for application as advanced supercapacitor electrodes.

Atomically Thin Mesoporous Nanomesh of Graphitic C₃N₄ for High-Efficiency Photocatalytic Hydrogen Evolution.

PubMed

Han, Qing; Wang, Bing; Gao, Jian; Cheng, Zhihua; Zhao, Yang; Zhang, Zhipan; Qu, Liangti

2016-02-23

Delamination of layer materials into two-dimensional single-atom sheets has induced exceptional physical properties, including large surface area, ultrahigh intrinsic carrier mobility, pronounced changes in the energy band structure, and other properties. Here, atomically thin mesoporous nanomesh of graphitic carbon nitride (g-C3N4) is fabricated by solvothermal exfoliation of mesoporous g-C3N4 bulk made from thermal polymerization of freeze-drying assembled Dicyandiamide nanostructure precursor. With the unique structural advantages for aligned energy levels, electron transfer, light harvesting, and the richly available reaction sites, the as-prepared monolayer of mesoporous g-C3N4 nanomesh exhibits a superior photocatalytic hydrogen evolution rate of 8510 μmol h(-1) g(-1) under λ > 420 nm and an apparent quantum efficiency of 5.1% at 420 nm, the highest of all the metal-free g-C3N4 nanosheets photocatalysts.

A study on pore-opening behaviors of graphite nanofibers by a chemical activation process.

PubMed

Kim, Byung-Joo; Lee, Young-Seak; Park, Soo-Jin

2007-02-15

In this work, porous graphite nanofibers (GNFs) were prepared by a KOH activation method in order to manufacture porous carbon nanofibers. The process was conducted in the activation temperature range of 900-1100 degrees C, and the KOH:GNFs ratio was fixed at 3.5:1. The textural properties of the porous carbons were analyzed using N2 adsorption isotherms at 77 K. The BET, D-R, and BJH equations were used to observe the specific surface areas and the micro- and mesopore structures, respectively. From the results, it was found that the textural properties, including the specific surface area and the pore volumes, were proportionally enhanced with increasing activation temperatures. However, the activation mechanisms showed quite significant differences between the samples activated at low and high temperatures.

Carbon/ λ-MnO 2 composites for supercapacitor electrodes

NASA Astrophysics Data System (ADS)

Malak-Polaczyk, A.; Matei-Ghimbeu, C.; Vix-Guterl, C.; Frackowiak, E.

2010-04-01

In the present work a composite of carbon with λ-MnO 2 have been synthesized by a simple two-step route. In the first step, to obtain LiMn 2O 4/carbon material, mesoporous activated carbon was impregnated with the solution of precursor metal salts and heated subsequently. As-prepared materials were acid treated which resulted in the formation of λ-MnO 2/carbon. Physical properties, structure and specific surface area of electrode materials were studied by TEM, X-ray diffraction and nitrogen sorption measurements. Voltammetry cycling, galvanostatic charge/discharge and impedance spectroscopy measurements performed in two- and three-electrode cells have been applied in order to measure electrochemical parameters. TEM images confirmed well dispersed λ-MnO 2 particles on the surface of carbon material. The carbon in the composite plays an important role as the surface area enhancing component and a support of pseudocapacitive material. Furthermore, the through-connected porosity serves as a continuous pathway for electrolyte transport. A synergetic effect of the porous carbon framework and of the redox properties of the λ-MnO 2 is at the origin of improvement of specific capacitance values which has been observed for composites after delithiation.

Protic-salt-derived nitrogen/sulfur-codoped mesoporous carbon for the oxygen reduction reaction and supercapacitors.

PubMed

Zhang, Shiguo; Ikoma, Ai; Ueno, Kazuhide; Chen, Zhengjian; Dokko, Kaoru; Watanabe, Masayoshi

2015-05-11

Nitrogen/sulfur-co-doped mesoporous carbon (Phen-HS) was obtained through direct carbonization of a single protic salt, that is, 1,10-phenanthrolinium dibisulfate ([Phen][2 HSO4 ]), in the presence of a colloidal silica template without the use of additional acid or metal catalysts for prepolymerization prior to carbonization. Phen-HS was prepared in a relatively high yield (30.0 %) and has a large surface area (1161 m(2)  g(-1) ), large pore volume (2.490 cm(3)  g(-1) ), large mesopores (≈12 nm), narrow pore-size distribution (7-16 nm), and high nitrogen (7.5 at %) and sulfur (1.3 at %) contents. The surface area/pore-size distribution is much higher/narrower than that of most reported carbon materials obtained from traditional precursors by using the same template. Phen-HS was directly used as an electrocatalyst for the oxygen reduction reaction (ORR) and as an electrode material for supercapacitors. As an efficient metal-free catalyst, Phen-HS exhibited good electrocatalytic activity toward the ORR in a 0.1 M KOH aqueous solution, which is comparable to the activity of a commercial Pt/C catalyst. Electrochemical measurements for Phen-HS used in a double-layer capacitor showed high specific capacitances of 160 and 140 F g(-1) in 1 M H2 SO4 and 6 M KOH, respectively, with good rate capabilities and high cycling stabilities. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Unusual Mesoporous Carbonaceous Matrix Loading with Sulfur as the Cathode of Lithium Sulfur Battery with Exceptionally Stable High Rate Performance.

PubMed

Qian, Weiwei; Gao, Qiuming; Li, Zeyu; Tian, Weiqian; Zhang, Hang; Zhang, Qiang

2017-08-30

Unusual three-dimensional mesoporous carbon/reduced graphene oxide (MP-C/rGO) matrix possessing graphene nanolayer pore walls built up by three to five graphene monosheets and some carbon particles with the sizes of about 5 nm located between the graphene nanolayers was prepared by facile freeze-drying and then carbonization of the poly(vinyl alcohol) and graphene oxide mixture. The mesoporous carbonaceous MP-C/rGO sample has a high specific surface area of 661.6 m 2 g -1 , large specific pore volume of 1.54 m 3 g -1 , and focused pore size distribution of 2-10 nm. About 64 wt % sulfur could be held in the pores of the MP-C/rGO matrix. As the cathode of a Li-S battery, the MP-C/rGO/S composite showed excellent electrochemical property including a high initial specific capacity of 919 mA h g -1 at 1 C with the capacity retention ratio of 63.3% and the Coulombic efficiency above 90% after 500 cycles. Meanwhile, the initial specific capacity of 602 mA h g -1 at 5 C and remaining capacity of 391 mA h g -1 after 500 cycles with an outstanding Coulombic efficiency of 97% indicate its exceptionally stable rate performance.

Enzymatic Conversion of CO2 to Bicarbonate in Functionalized Mesoporous Silica

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

Yu, Yuehua; Chen, Baowei; Qi, Wen N.

2012-05-01

We report here that carbonic anhydrase (CA), the fastest enzyme that can covert carbon dioxide to bicarbonate, can be spontaneously entrapped in functionalized mesoporous silica (FMS) with super-high loading density (up to 0.5 mg of protein/mg of FMS) due to the dominant electrostatic interaction. The binding of CA to HOOC-FMS can result in the protein’s conformational change comparing to the enzyme free in solution, but can be overcome with increased protein loading density. The higher the protein loading density, the less conformational change, hence the higher enzymatic activity and the higher enzyme immobilization efficiency. The electrostatically bound CA can bemore » released by changing pH. The released enzyme still displayed the native conformational structure and the same high enzymatic activity as that prior to the enzyme entrapment. This work opens up a new approach converting carbon dioxide to biocarbonate in a biomimetic nanoconfiguration that can be integrated with the other part of biosynthesis process for the assimilation of carbon dioxide.« less

Nano-structured silica coated mesoporous carbon micro-granules for potential application in water filtration

NASA Astrophysics Data System (ADS)

Das, Avik; Sen, D.; Mazumder, S.; Ghosh, A. K.

2017-05-01

A novel nano-composite spherical micro-granule has been synthesized using a facile technique of solvent evaporation induced assembly of nanoparticles for potential application in water filtration. The spherical micro-granule is comprised of nano-structured shell of hydrophilic silica encapsulating a hydrophobic mesoporous carbon at the core. Hierarchical structure of such core-shell micro-granules has been rigorously characterized using small-angle neutron and X-ray scattering techniques and complemented with scanning electron microscopy. The hydrophilic silica envelope around the carbon core helps in incorporation of such granules into the hydrophilic polymeric ultra-filtration membrane. The interstitial micro-pores present in the silica shell can serve as water transport channels and the mesoporus carbon core enhances the separation performance due its well adsorption characteristics. It has been found that the incorporation of such granules inside the ultra-filtration membrane indeed enhances the water permeability as well as the separation performance in a significant way.

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

PubMed Central

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

2015-01-01

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

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

NASA Astrophysics Data System (ADS)

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

2012-09-01

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

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

PubMed

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

2015-02-04

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.

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

PubMed Central

Huo, Chengli; Ouyang, Jing; Yang, Huaming

2014-01-01

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

Facile and green synthesis of mesoporous Co3O4 nanocubes and their applications for supercapacitors

NASA Astrophysics Data System (ADS)

Liu, Xiangmei; Long, Qing; Jiang, Chunhui; Zhan, Beibei; Li, Chen; Liu, Shujuan; Zhao, Qiang; Huang, Wei; Dong, Xiaochen

2013-06-01

Nanostructured Co3O4 materials attracted significant attention due to their exceptional electrochemical (pseudo-capacitive) properties. However, rigorous preparation conditions are needed to control the size (especially nanosize), morphology and size distribution of the products obtained by conventional methods. Herein, we describe a novel one step shape-controlled synthesis of uniform Co3O4 nanocubes with a size of 50 nm with the existence of mesoporous carbon nanorods (meso-CNRs). In this synthesis process, meso-CNRs not only act as a heat receiver to directly obtain Co3O4 eliminating the high-temperature post-calcination, but also control the morphology of the resulting Co3O4 to form nanocubes with uniform distribution. More strikingly, mesoporous Co3O4 nanocubes are obtained by further thermal treatment. The structure and morphology of the samples were characterized by scanning electron microscopy, transmission electron microscopy and X-ray diffraction. A possible formation mechanism of mesoporous Co3O4 nanocubes is proposed here. Electrochemical tests have revealed that the prepared mesoporous Co3O4 nanocubes demonstrate a remarkable performance in supercapacitor applications due to the porous structure, which endows fast ion and electron transfer.Nanostructured Co3O4 materials attracted significant attention due to their exceptional electrochemical (pseudo-capacitive) properties. However, rigorous preparation conditions are needed to control the size (especially nanosize), morphology and size distribution of the products obtained by conventional methods. Herein, we describe a novel one step shape-controlled synthesis of uniform Co3O4 nanocubes with a size of 50 nm with the existence of mesoporous carbon nanorods (meso-CNRs). In this synthesis process, meso-CNRs not only act as a heat receiver to directly obtain Co3O4 eliminating the high-temperature post-calcination, but also control the morphology of the resulting Co3O4 to form nanocubes with uniform distribution. More strikingly, mesoporous Co3O4 nanocubes are obtained by further thermal treatment. The structure and morphology of the samples were characterized by scanning electron microscopy, transmission electron microscopy and X-ray diffraction. A possible formation mechanism of mesoporous Co3O4 nanocubes is proposed here. Electrochemical tests have revealed that the prepared mesoporous Co3O4 nanocubes demonstrate a remarkable performance in supercapacitor applications due to the porous structure, which endows fast ion and electron transfer. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr00495c

Generalised syntheses of ordered mesoporous oxides: the atrane route

NASA Astrophysics Data System (ADS)

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

2000-06-01

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

Periodically Arranged Arrays of Dendritic Pt Nanospheres Using Cage-Type Mesoporous Silica as a Hard Template.

PubMed

Kani, Kenya; Malgras, Victor; Jiang, Bo; Hossain, Md Shahriar A; Alshehri, Saad M; Ahamad, Tansir; Salunkhe, Rahul R; Huang, Zhenguo; Yamauchi, Yusuke

2018-01-04

Dendritic Pt nanospheres of 20 nm diameter are synthesized by using a highly concentrated surfactant assembly within the large-sized cage-type mesopores of mesoporous silica (LP-FDU-12). After diluting the surfactant solution with ethanol, the lower viscosity leads to an improved penetration inside the mesopores. After Pt deposition followed by template removal, the arrangement of the Pt nanospheres is a replication from that of the mesopores in the original LP-FDU-12 template. Although it is well known that ordered LLCs can form on flat substrates, the confined space inside the mesopores hinders surfactant self-organization. Therefore, the Pt nanospheres possess a dendritic porous structure over the entire area. The distortion observed in some nanospheres is attributed to the close proximity existing between neighboring cage-type mesopores. This new type of nanoporous metal with a hierarchical architecture holds potential to enhance substance diffusivity/accessibility for further improvement of catalytic activity. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Controlled growth of CNT in mesoporous AAO through optimized conditions for membrane preparation and CVD operation

NASA Astrophysics Data System (ADS)

Ciambelli, P.; Arurault, L.; Sarno, M.; Fontorbes, S.; Leone, C.; Datas, L.; Sannino, D.; Lenormand, P.; Le Blond Du Plouy, S.

2011-07-01

Anodic aluminium oxide (RAAO) membranes with a mesoporous structure were prepared under strictly controlling experimental process conditions, and physically and chemically characterized by a wide range of experimental techniques. Commercial anodic aluminium oxide (CAAO) membranes were also investigated for comparison. We demonstrated that RAAO membranes have lower content of both water and phosphorus and showed better porosity shape than CAAO. The RAAO membranes were used for template growth of carbon nanotubes (CNT) inside its pores by ethylene chemical vapour deposition (CVD) in the absence of a catalyst. A composite material, containing one nanotube for each channel, having the same length as the membrane thickness and an external diameter close to the diameter of the membrane holes, was obtained. Yield, selectivity and quality of CNTs in terms of diameter, length and arrangement (i.e. number of tubes for each channel) were optimized by investigating the effect of changing the experimental conditions for the CVD process. We showed that upon thermal treatment RAAO membranes were made up of crystallized allotropic alumina phases, which govern the subsequent CNT growth, because of their catalytic activity, likely due to their Lewis acidity. The strict control of experimental conditions for membrane preparation and CNT growth allowed us to enhance the carbon structural order, which is a critical requisite for CNT application as a substitute for copper in novel nano-interconnects.

Controlled growth of CNT in mesoporous AAO through optimized conditions for membrane preparation and CVD operation.

PubMed

Ciambelli, P; Arurault, L; Sarno, M; Fontorbes, S; Leone, C; Datas, L; Sannino, D; Lenormand, P; Du Plouy, S Le Blond

2011-07-01

Anodic aluminium oxide (RAAO) membranes with a mesoporous structure were prepared under strictly controlling experimental process conditions, and physically and chemically characterized by a wide range of experimental techniques. Commercial anodic aluminium oxide (CAAO) membranes were also investigated for comparison. We demonstrated that RAAO membranes have lower content of both water and phosphorus and showed better porosity shape than CAAO. The RAAO membranes were used for template growth of carbon nanotubes (CNT) inside its pores by ethylene chemical vapour deposition (CVD) in the absence of a catalyst. A composite material, containing one nanotube for each channel, having the same length as the membrane thickness and an external diameter close to the diameter of the membrane holes, was obtained. Yield, selectivity and quality of CNTs in terms of diameter, length and arrangement (i.e. number of tubes for each channel) were optimized by investigating the effect of changing the experimental conditions for the CVD process. We showed that upon thermal treatment RAAO membranes were made up of crystallized allotropic alumina phases, which govern the subsequent CNT growth, because of their catalytic activity, likely due to their Lewis acidity. The strict control of experimental conditions for membrane preparation and CNT growth allowed us to enhance the carbon structural order, which is a critical requisite for CNT application as a substitute for copper in novel nano-interconnects.

Functionalization of mesoporous materials for lanthanide and actinide extraction.

PubMed

Florek, Justyna; Giret, Simon; Juère, Estelle; Larivière, Dominic; Kleitz, Freddy

2016-10-14

Among the energy sources currently available that could address our insatiable appetite for energy and minimize our CO2 emission, solar, wind, and nuclear energy currently occupy an increasing portion of our energy portfolio. The energy associated with these sources can however only be harnessed after mineral resources containing valuable constituents such as actinides (Ac) and rare earth elements (REEs) are extracted, purified and transformed into components necessary for the conversion of energy into electricity. Unfortunately, the environmental impacts resulting from their manufacture including the generation of undesirable and, sometimes, radioactive wastes and the non-renewable nature of the mineral resources, to name a few, have emerged as challenges that should be addressed by the scientific community. In this perspective, the recent development of functionalized solid materials dedicated to selective elemental separation/pre-concentration could provide answers to several of the above-mentioned challenges. This review focuses on recent advances in the field of mesoporous solid-phase (SP) sorbents designed for REEs and Ac liquid-solid extraction. Particular attention will be devoted to silica and carbon sorbents functionalized with commonly known ligands, such as phosphorus or amide-containing functionalities. The extraction performances of these new systems are discussed in terms of sorption capacity and selectivity. In order to support potential industrial applications of the silica and carbon-based sorbents, their main drawbacks and advantages are highlighted and discussed.

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

PubMed

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

2016-05-20

Inspired by the attractive catalytic properties of palladium and the inert nature of carbon supports in catalysis, a concise and simple methodology for in situ nitrogen-doped mesoporous-carbon-supported palladium nanoparticles (Pd/N-C) has been developed by carbonizing a palladium dimethylglyoximate complex. The as-synthesized Pd/N-C has been exfoliated as a fuel cell catalyst by studying the electro-oxidation of methanol and formic acid. The material synthesized at 400 °C,namely, Pd/N-C-400,exhibitssuperior mass activity and stability among catalysts synthesized under different carbonization temperaturesbetween300 and 500 °C. The unique 1D porous structure in Pd/N-C-400 helps better electron transport at the electrode surface, which eventually leads to about five times better catalytic activity and about two times higher stability than that of commercial Pd/C. Thus, our designed sacrificial metal-organic templatedirected pathway becomes a promising technique for Pd/N-C synthesis with superior catalytic performances. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Controllable synthesis of mesoporous Co{sub 3}O{sub 4} nanoflake array and its application for supercapacitor

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

Xiao, Anguo, E-mail: hixiaoanguo@126.com; Zhou, Shibiao; Zuo, Chenggang

Graphical abstract: Electrodeposited mesoporous Co{sub 3}O{sub 4} nanoflake arrays exhibit porous structure composed of mesoporous nanoflakes and high supercapacitor performance. - Highlights: • Mesoporous Co{sub 3}O{sub 4} nanoflake arrays are prepared via electrodeposition method. • Mesoporous nanowall arrays are favorable for fast ion/electron transfer. • Mesoporous Co{sub 3}O{sub 4} nanoflake arrays show excellent supercapacitor performance. - Abstract: A mesoporous Co{sub 3}O{sub 4} nanoflake array grown on carbon cloth is prepared by a facile electrodeposition method with a following annealing process. The as-prepared Co{sub 3}O{sub 4} nanoflake possesses a continuous mesopores ranging from 2 to 5 nm and grows tightly onmore » the substrate forming a porous net-like structure with macropores of 20–200 nm. The electrochemical performance of the mesoporous Co{sub 3}O{sub 4} nanoflake arrays as pseudocapcitor electrode are investigated by cyclic voltammograms and galvanostatic charge/discharge tests in 2 M KOH. The as-prepared Co{sub 3}O{sub 4} array exhibits a high discharge capacitance and excellent rate capability with 450 F g{sup −1}, 436 F g{sup −1}, 408 F g{sup −1}, 380 F g{sup −1}and 363 F g{sup −1} at 1, 2, 4, 10, and 20 A g{sup −1}, respectively. The specific capacitance of 81% is maintained from 1 A g{sup −1} to 20 A g{sup −1}. The electrode also shows rather good cycling stability and exhibits a specific capacitance of 414 F g{sup −1} after 5000 cycles.« less

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

PubMed Central

2014-01-01

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

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

PubMed

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

2018-01-10

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

Microwave pyrolysis with KOH/NaOH mixture activation: A new approach to produce micro-mesoporous activated carbon for textile dye adsorption.

PubMed

Liew, Rock Keey; Azwar, Elfina; Yek, Peter Nai Yuh; Lim, Xin Yi; Cheng, Chin Kui; Ng, Jo-Han; Jusoh, Ahmad; Lam, Wei Haur; Ibrahim, Mohd Danial; Ma, Nyuk Ling; Lam, Su Shiung

2018-06-19

A micro-mesoporous activated carbon (AC) was produced via an innovative approach combining microwave pyrolysis and chemical activation using NaOH/KOH mixture. The pyrolysis was examined over different chemical impregnation ratio, microwave power, microwave irradiation time and types of activating agents for the yield, chemical composition, and porous characteristic of the AC obtained. The AC was then tested for its feasibility as textile dye adsorbent. About 29 wt% yield of AC was obtained from the banana peel with low ash and moisture (<5 wt%), and showed a micro-mesoporous structure with high BET surface area (≤1038 m 2 /g) and pore volume (≤0.80 cm 3 /g), indicating that it can be utilized as adsorbent to remove dye. Up to 90% adsorption of malachite green dye was achieved by the AC. Our results indicate that the microwave-activation approach represents a promising attempt to produce good quality AC for dye adsorption. Copyright © 2018 Elsevier Ltd. All rights reserved.

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

PubMed Central

Park, Seok-Hwan; Lee, Wan-Jin

2015-01-01

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

Improving the corrosion resistance of proton exchange membrane fuel cell carbon supports by pentafluorophenyl surface functionalization

NASA Astrophysics Data System (ADS)

Forouzandeh, Farisa; Li, Xiaoan; Banham, Dustin W.; Feng, Fangxia; Joseph Kakanat, Abraham; Ye, Siyu; Birss, Viola

2018-02-01

In this study, the effect of surface functionalization on the electrochemical corrosion resistance of a high surface area, mesoporous colloid imprinted carbon powder (CIC), as well as microporous Vulcan carbon (VC, serving as the benchmark), was demonstrated, primarily for PEM fuel cell applications. CIC-22, which is highly hydrophilic and was synthesized with 22 nm silica colloid templates, and as-received, mildly hydrophobic, VC powders, were functionalized with 2,3,4,5,6-pentafluorophenyl (-PhF5) surface groups using a straightforward diazonium reduction reaction. These carbons were then subjected to corrosion testing, involving a potential cycling-step sequence in room temperature 0.5 M H2SO4. Using cyclic voltammetry and charge/time analysis, the double layer and pseudo-capacitive gravimetric charges of the carbons, prior to and after the application of these potential steps, were tracked in order to obtain information about surface area changes and the extent of carbon oxidation, respectively. It is shown that the corrosion resistance was improved by ca. 50-80% by surface functionalization, likely due to a combination of surface passivation (loss of carbon active sites) and increased surface hydrophobicity.

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

Chung, Po-Wen

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

Photodegradation of methyl red under visible light by mesoporous carbon nitride

NASA Astrophysics Data System (ADS)

Hu, Yueyue; Zhang, Min; Xiao, Zaozao; Jiang, Tao; Yan, Bing; Li, Jian

2018-02-01

Mesoporous carbon nitride (mpg-C3N4) with tunable microstructure has been successfully prepared through a simple polymerization reaction of cyanamide by a nano hard-templating approach. The obtained materials have been characterized using X-ray diffraction (XRD), N2 adsorption, and Fourier transform infrared (FT-IR) spectroscopy. The results show that the pore diameter of the mpg-C3N4 materials can be easily tuned from 3.8 to 10.5 nm. The mpg-C3N4 materials are demonstrated to exhibit much higher visible light photocatalytic activity than that of g-C3N4 for the degradation of aqueous methyl red (MR). The high surface areas and large pore volume contributed to the efficient visible light photocatalytic activity.

Inverse opal carbons for counter electrode of dye-sensitized solar cells.

PubMed

Kang, Da-Young; Lee, Youngshin; Cho, Chang-Yeol; Moon, Jun Hyuk

2012-05-01

We investigated the fabrication of inverse opal carbon counter electrodes using a colloidal templating method for DSSCs. Specifically, bare inverse opal carbon, mesopore-incoporated inverse opal carbon, and graphitized inverse opal carbon were synthesized and stably dispersed in ethanol solution for spray coating on a FTO substrate. The thickness of the electrode was controlled by the number of coatings, and the average relative thickness was evaluated by measuring the transmittance spectrum. The effect of the counter electrode thickness on the photovoltaic performance of the DSSCs was investigated and analyzed by interfacial charge transfer resistance (R(CT)) under EIS measurement. The effect of the surface area and conductivity of the inverse opal was also investigated by considering the increase in surface area due to the mesopore in the inverse opal carbon and conductivity by graphitization of the carbon matrix. The results showed that the FF and thereby the efficiency of DSSCs were increased as the electrode thickness increased. Consequently, the larger FF and thereby the greater efficiency of the DSSCs were achieved for mIOC and gIOC compared to IOC, which was attributed to the lower R(CT). Finally, compared to a conventional Pt counter electrode, the inverse opal-based carbon showed a comparable efficiency upon application to DSSCs.

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

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

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

2009-07-15

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

Formation of carbon nanosheets via simultaneous activation and catalytic carbonization of macroporous anion-exchange resin for supercapacitors application.

PubMed

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

2014-12-10

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).

Preparation of a Si/SiO2 -Ordered-Mesoporous-Carbon Nanocomposite as an Anode for High-Performance Lithium-Ion and Sodium-Ion Batteries.

PubMed

Zeng, Lingxing; Liu, Renpin; Han, Lei; Luo, Fenqiang; Chen, Xi; Wang, Jianbiao; Qian, Qingrong; Chen, Qinghua; Wei, Mingdeng

2018-04-03

In this work, an Si/SiO 2 -ordered-mesoporous carbon (Si/SiO 2 -OMC) nanocomposite was initially fabricated through a magnesiothermic reduction strategy by using a two-dimensional bicontinuous mesochannel of SiO 2 -OMC as a precursor, combined with an NaOH etching process, in which crystal Si/amorphous SiO 2 nanoparticles were encapsulated into the OMC matrix. Not only can such unique porous crystal Si/amorphous SiO 2 nanoparticles uniformly dispersed in the OMC matrix mitigate the volume change of active materials during the cycling process, but they can also improve electrical conductivity of Si/SiO 2 and facilitate the Li + /Na + diffusion. When applied as an anode for lithium-ion batteries (LIBs), the Si/SiO 2 -OMC composite displayed superior reversible capacity (958 mA h g -1 at 0.2 A g -1 after 100 cycles) and good cycling life (retaining a capacity of 459 mA h g -1 at 2 A g -1 after 1000 cycles). For sodium-ion batteries (SIBs), the composite maintained a high capacity of 423 mA h g -1 after 100 cycles at 0.05 A g -1 and an extremely stable reversible capacity of 190 mA h g -1 was retained even after 500 cycles at 1 A g -1 . This performance is one of the best long-term cycling properties of Si-based SIB anode materials. The Si/SiO 2 -OMC composites exhibited great potential as an alternative material for both lithium- and sodium-ion battery anodes. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Hydrogen production by steam reforming of liquefied natural gas (LNG) over nickel catalysts supported on cationic surfactant-templated mesoporous aluminas

NASA Astrophysics Data System (ADS)

Seo, Jeong Gil; Youn, Min Hye; Park, Sunyoung; Jung, Ji Chul; Kim, Pil; Chung, Jin Suk; Song, In Kyu

Two types of mesoporous γ-aluminas (denoted as A-A and A-S) are prepared by a hydrothermal method under different basic conditions using cationic surfactant (cetyltrimethylammonium bromide, CTAB) as a templating agent. A-A and A-S are synthesized in a medium of ammonia solution and sodium hydroxide solution, respectively. Ni/γ-Al 2O 3 catalysts (Ni/A-A and Ni/A-S) are then prepared by an impregnation method, and are applied to hydrogen production by steam reforming of liquefied natural gas (LNG). The effect of a mesoporous γ-Al 2O 3 support on the catalytic performance of Ni/γ-Al 2O 3 is investigated. The identity of basic solution strongly affects the physical properties of the A-A and A-S supports. The high surface-area of the mesoporous γ-aluminas and the strong metal-support interaction of supported catalysts greatly enhance the dispersion of nickel species on the catalyst surface. The well-developed mesopores of the Ni/A-A and Ni/A-S catalysts prohibit the polymerization of carbon species on the catalyst surface during the reaction. In the steam reforming of LNG, both Ni/A-A and Ni/A-S catalysts give better catalytic performance than the nickel catalyst supported on commercial γ-Al 2O 3 (Ni/A-C). In addition, the Ni/A-A catalyst is superior to the Ni/A-S catalyst. The relatively strong metal-support interaction of Ni/A-A catalyst effectively suppresses the sintering of metallic nickel and the carbon deposition in the steam reforming of LNG. The large pores of the Ni/A-A catalyst also play an important role in enhancing internal mass transfer during the reaction.

Ultrasensitive electrochemical immunosensors for multiplexed determination using mesoporous platinum nanoparticles as nonenzymatic labels.

PubMed

Cui, Zhentao; Wu, Dan; Zhang, Yong; Ma, Hongmin; Li, He; Du, Bin; Wei, Qin; Ju, Huangxian

2014-01-07

An ultrasensitive multiplexed immunoassay method was developed at a disposable immunosensor array using mesoporous platinum nanoparticles (M-Pt NPs) as nonenzymatic labels. M-Pt NPs were prepared by ultrasonic method and employed to label the secondary antibody (Ab2) for signal amplification. The immunosensor array was constructed by covalently immobilizing capture antibody (Ab1) on graphene modified screen printed carbon electrodes (SPECs). After the sandwich-type immunoreactions, the M-Pt-Ab2 was bound to immunosensor surface to catalyze the electro-reduction of H2O2 reaction, which produced detectable signals for readout of analytes. Using breast cancer related panel of tumor markers (CA125, CA153 and CEA) as model analytes, this method showed wide linear ranges of over 4 orders of magnitude with the detection limits of 0.002 U mL(-1), 0.001 U mL(-1) and 7.0 pg mL(-1) for CA125, CA153 and CEA, respectively. The disposable immunosensor array possessed excellent clinical value in cancer screening as well as convenient point of care diagnostics. Copyright © 2013 Elsevier B.V. All rights reserved.

Carbon with hierarchical pores from carbonized metal-organic frameworks for lithium sulphur batteries.

PubMed

Xi, Kai; Cao, Shuai; Peng, Xiaoyu; Ducati, Caterina; Kumar, R Vasant; Cheetham, Anthony K

2013-03-18

This paper presents a novel method and rationale for utilizing carbonized MOFs for sulphur loading to fabricate cathode structures for lithium-sulphur batteries. Unique carbon materials with differing hierarchical pore structures were synthesized from four types of zinc-containing metal-organic frameworks (MOFs). It is found that cathode materials made from MOFs-derived carbons with higher mesopore (2-50 nm) volumes exhibit increased initial discharge capacities, whereas carbons with higher micropore (<2 nm) volumes lead to cathode materials with better cycle stability.

Facile synthesis and unique physicochemical properties of three-dimensionally ordered macroporous magnesium oxide, gamma-alumina, and ceria-zirconia solid solutions with crystalline mesoporous walls.

PubMed

Li, Huining; Zhang, Lei; Dai, Hongxing; He, Hong

2009-05-18

Three-dimensionally (3D) ordered macroporous (3DOM) MgO, gamma-Al(2)O(3), Ce(0.6)Zr(0.4)O(2), and Ce(0.7)Zr(0.3)O(2) with polycrystalline mesoporous walls have been successfully fabricated with the triblock copolymer EO(106)PO(70)EO(106) (Pluronic F127) and regularly packed monodispersive polymethyl methacrylate (PMMA) microspheres as the template and magnesium, aluminum, cerium and zirconium nitrate(s), or aluminum isopropoxide as the metal source. The as-synthesized metal oxides were characterized by means of techniques such as X-ray diffraction (XRD), thermogravimetric analysis/differential scanning calorimetry (TGA/DSC), Fourier transform infrared (FT-IR), high-resolution scanning electron microscopy (HRSEM), high-resolution transmission electron microscopy/selected area electron diffraction (HRTEM/SAED), BET, carbon dioxide temperature-programmed desorption (CO(2)-TPD), and hydrogen temperature-programmed reduction (H(2)-TPR). It is shown that the as-fabricated MgO, gamma-Al(2)O(3), Ce(0.6)Zr(0.4)O(2), and Ce(0.7)Zr(0.3)O(2) samples possessed single-phase polycrystalline structures and displayed a 3DOM architecture; the MgO, Ce(0.6)Zr(0.4)O(2), and Ce(0.7)Zr(0.3)O(2) samples exhibited worm-hole-like mesoporous walls, whereas the gamma-Al(2)O(3) samples exhibited 3D ordered mesoporous walls. The solvent (ethanol or water) nature and concentration, metal precursor, surfactant, and drying condition have an important impact on the pore structure and surface area of the final product. The introduction of surfactant F127 to the synthesis system could significantly enhance the surface areas of the 3DOM metal oxides. With PMMA and F127 in a 40% ethanol solution, one can generate well-arrayed 3DOM MgO with a surface area of 243 m(2)/g and 3DOM Ce(0.6)Zr(0.4)O(2) with a surface area of 100 m(2)/g; with PMMA and F127 in an ethanol-HNO(3) solution, one can obtain 3DOM gamma-Al(2)O(3)with a surface area of 145 m(2)/g. The 3DOM MgO and 3DOM gamma-Al(2)O(3) samples showed excellent CO(2) adsorption behaviors, whereas the 3DOM Ce(0.6)Zr(0.4)O(2) sample exhibited exceptional low-temperature reducibility. The unique physicochemical properties associated with the copresence of 3DOM and mesoporous walls make these porous materials ideal candidates for applications in heterogeneous catalysis and CO(2) adsorption.

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

PubMed

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

2011-01-25

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

Heteroatom Polymer-Derived 3D High-Surface-Area and Mesoporous Graphene Sheet-Like Carbon for Supercapacitors.

PubMed

Sheng, Haiyang; Wei, Min; D'Aloia, Alyssa; Wu, Gang

2016-11-09

Current supercapacitors suffer from low energy density mainly due to the high degree of microporosity and insufficient hydrophilicity of their carbon electrodes. Development of a supercapacitor capable of simultaneously storing as much energy as a battery, along with providing sufficient power and long cycle stability would be valued for energy storage applications and innovations. Differing from commonly studied reduced graphene oxides, in this work we identified an inexpensive heteroatom polymer (polyaniline-PANI) as a carbon/nitrogen precursor, and applied a controlled thermal treatment at elevated temperature to convert PANI into 3D high-surface-area graphene-sheet-like carbon materials. During the carbonization process, various transition metals including Fe, Co, and Ni were added, which play critical roles in both catalyzing the graphitization and serving as pore forming agents. Factors including post-treatments, heating temperatures, and types of metal were found crucial for achieving enhanced capacitance performance on resulting carbon materials. Using FeCl 3 as precursor along with optimal heating temperature 1000 °C and mixed acid treatment (HCl+HNO 3 ), the highest Brunauer-Emmett-Teller (BET) surface area of 1645 m 2 g -1 was achieved on the mesopore dominant graphene-sheet-like carbon materials. The unique morphologies featured with high-surface areas, dominant mesopores, proper nitrogen doping, and 3D graphene-like structures correspond to remarkably enhanced electrochemical specific capacitance up to 478 Fg -1 in 1.0 M KOH at a scan rate of 5 mV s -1 . Furthermore, in a real two-electrode system of a symmetric supercapacitor, a specific capacitance of 235 Fg -1 using Nafion binder is obtained under a current density of 1 Ag -1 by galvanostatic charge-discharge tests in 6.0 M KOH. Long-term cycle stability up to 5000 cycles by using PVDF binder in electrode was systematically evaluated as a function of types of metals and current densities.

Facile synthesis of mesoporous silica sublayer with hierarchical pore structure on ceramic membrane using anionic polyelectrolyte.

PubMed

Kang, Taewook; Oh, Seogil; Kim, Honggon; Yi, Jongheop

2005-06-21

A facile method for introducing mesoporous silica sublayer onto the surface of a ceramic membrane for use in liquid-phase separation is described. To reduce the electrostatic repulsion between the mesoporous silica sol and the ceramic membrane in highly acidic conditions (pH < 2), thus facilitating the approach of hydrolyzed silica sol to the surface of the membrane, poly(sodium 4-styrenesulfonate) (Na+PSS-, denoted as PSS-) was used as an ionic linker. The use of PSS- led to a significant reduction in positive charge on the ceramic membrane, as confirmed by experimental titration data. Consistent with the titration results, the amount of mesoporous silica particles on the surface of the ceramic membrane was low, in the absence of PSS- treatment, whereas mesoporous silica sublayer with hierarchical pore structure was produced, when 1 wt % PSS- was used. The results show that mesoporous silica grows in the confined surface, eventually forming a multistacked surface architecture. The mesoporous silica sublayer contained uniform, ordered (P6 mm) mesopores of ca. 7.5 nm from mesoporous silica as well as macropores ( approximately mum) from interparticle voids, as evidenced by transmission electron microscopy and scanning electron microscopy analyses. The morphologies of the supported mesoporous silica could be manipulated, thus permitting the generation of uniform needlelike forms or uniform spheroid particles by varying the concentration of PSS-.

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

Zhang, Jinshui; Qiao, Zhenan -An; Mahurin, Shannon Mark

A soft chemistry synthetic strategy based on a Friedel Crafts alkylation reaction is developed for the textural engineering of phenolic resin (PR) with a robust mesoporous framework to avoid serious framework shrinkage and maximize retention of organic functional moieties. By taking advantage of the structural benefits of molecular bridges, the resultant sample maintains a bimodal micro-mesoporous architecture with well-preserved organic functional groups, which is effective for carbon capture. Furthermore, this soft chemistry synthetic protocol can be further extended to nanotexture other aromatic-based polymers with robust frameworks.

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

PubMed

Yamauchi, Yusuke; Kuroda, Kazuyuki

2008-04-07

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

Preparation of carbon-functionalized magnetic graphene/mesoporous silica composites for selective extraction of miglitol and voglibose in rat plasma.

PubMed

Liu, Xiaodan; Feng, Jianan; Li, Yan

2018-05-15

In this work, magnetic graphene/mesoporous silica composites with carbon-functionalized pore-walls (denoted as MG@mSiO 2 -C composites) were synthesized and applied as restricted access matrix solid phase extraction (RAM-SPE) adsorbents for the determination of miglitol and voglibose in rat plasma by LC-MS/MS. The MG@mSiO 2 -C composites were synthesized by using the template (Cetyltrimethyl Ammonium Bromide, CTAB) as carbon source with sulfuric acid pretreated. The obtained nano-composites were proven to have many unique properties such as large specific surface area of 277.1 cm 2 g -1 , uniform mesopores with average pore size of 3.35 nm, and carbon-functionalized pore-walls. Taking advantage of the hydrophilic interaction between carbon and glycans, α-glucosidase inhibitors (miglitol and voglibose) could be directly extracted from rat plasma with no need of other pre-treatment procedures. The SPE conditions such as the adsorbent amount, elution solvent type, adsorption time and elution time were optimized. For both miglitol and voglibose, good linearities of 10-2000 ng mL -1 were obtained with determination coefficients (R 2 ) > 0.99. The intra-day and inter-day RSDs were 3.3-6.9% (n = 6) and 6.0-8.0% (n = 6), respectively. The recoveries were in the range of 99.9-100.4% and the sensitivities were as low as 2-2.5 ng mL -1 (LOD). This MG@mSiO 2 -C composites-based RAM-SPE method offers high extraction efficiency for the determination of α-glucosidase inhibitor in plasma. Copyright © 2018 Elsevier B.V. All rights reserved.

Block copolymer directed one-pot simple synthesis of L10-phase FePt nanoparticles inside ordered mesoporous aluminosilicate/carbon composites.

PubMed

Kang, Eunae; Jung, Hyunok; Park, Je-Geun; Kwon, Seungchul; Shim, Jongmin; Sai, Hiroaki; Wiesner, Ulich; Kim, Jin Kon; Lee, Jinwoo

2011-02-22

A "one-pot" synthetic method was developed to produce L1(0)-phase FePt nanoparticles in ordered mesostructured aluminosilicate/carbon composites using polyisoprene-block-poly(ethylene oxide) (PI-b-PEO) as a structure-directing agent. PI-b-PEO block copolymers with aluminosilicate sols are self-assembled with a hydrophobic iron precursor (dimethylaminomethyl-ferrocene) and a hydrophobic platinum precursor (dimethyl(1,5-cyclooctadiene)platinum(II)) to obtain mesostructured composites. The as-synthesized material was heat-treated to 800 °C under an Ar/H(2) mixture (5% v/v), resulting in the formation of fct FePt nanocrystals encapsulated in ordered mesopores. By changing the quantities of the Fe and Pt precursors in the composite materials, the average particle size of the resulting fct FePt, estimated using the Debye-Scherer equation with X-ray diffraction patterns, can be easily controlled to be 2.6-10.4 nm. Using this simple synthetic method, we can extend the size of directly synthesized fct FePt up to ∼10 nm, which cannot be achieved directly in the colloidal synthetic method. All fct FePt nanoparticles show hysteresis behavior at room temperature, which indicates that ferromagnetic particles are obtained inside mesostructued channels. Well-isolated, ∼10 nm fct FePt have a coercivity of 1100 Oe at 300 K. This coercivity value is higher than values of fct FePt nanoparticles synthesized through the tedious hard template method by employing SBA-15 as a host material. The coercivity value for FePt-1 (2.6 nm) at 5 K is as high as 11 900 Oe, which is one of the largest values reported for FePt nanoparticles, or any other magnetic nanoparticles. The fct FePt nanoparticles also showed exchange-bias behavior.

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

PubMed

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

2014-11-07

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

Highly efficient and recyclable basic mesoporous zeolite catalyzed condensation, hydroxylation, and cycloaddition reactions.

PubMed

Sarmah, Bhaskar; Satpati, Biswarup; Srivastava, Rajendra

2017-05-01

Crystalline mesoporous ZSM-5 zeolite was prepared in the presence of 1,4-diazabicyclo[2.2.2]octane derived multi-cationic structure directing agent. The calcined form of the mesoprous zeolite was treated with NH 4 OH to obtain basic mesoporous ZSM-5. Catalyst was characterized by the complementary combination of X-ray diffraction, N 2 -adsorption, electron microscopes, and temperature programme desorption techniques. Catalytic activity of the basic mesoporous ZSM-5 was systematically assessed using Knoevenagel condensation reaction for the synthesis a wide range of substituted styrene. Applications of the catalyst were investigated in the benzamide hydroxylation for the synthesis of carbinolamides and one-pot, multi-component condensation reaction for the synthesis of naphthopyrans. Finally, the catalyst was evaluated in the cycloaddition of CO 2 to epoxide for the synthesis of cyclic carbonates. Recycling study shows that no significant decrease in the catalytic activity was observed after five recycles. Copyright © 2017. Published by Elsevier Inc.

TiO2 nanotubes and mesoporous silica as containers in self-healing epoxy coatings

PubMed Central

Vijayan P., Poornima; Al-Maadeed, Mariam Ali S. A.

2016-01-01

The potential of inorganic nanomaterials as reservoirs for healing agents is presented here. Mesoporous silica (SBA-15) and TiO2 nanotubes (TNTs) were synthesized. Both epoxy-encapsulated TiO2 nanotubes and amine-immobilized mesoporous silica were incorporated into epoxy and subsequently coated on a carbon steel substrate. The encapsulated TiO2 nanotubes was quantitatively estimated using a ‘dead pore ratio’ calculation. The morphology of the composite coating was studied in detail using transmission electron microscopic (TEM) analysis. The self-healing ability of the coating was monitored using electrochemical impedance spectroscopy (EIS); the coating recovered 57% of its anticorrosive property in 5 days. The self-healing of the scratch on the coating was monitored using Scanning Electron Microscopy (SEM). The results confirmed that the epoxy pre-polymer was slowly released into the crack. The released epoxy pre-polymer came into contact with the amine immobilized in mesoporous silica and cross-linked to heal the scratch. PMID:27941829

From microporous regular frameworks to mesoporous materials with ultrahigh surface area: dynamic reorganization of porous polymer networks.

PubMed

Kuhn, Pierre; Forget, Aurélien; Su, Dangsheng; Thomas, Arne; Antonietti, Markus

2008-10-08

High surface area organic materials featuring both micro- and mesopores were synthesized under ionothermal conditions via the formation of polyaryltriazine networks. While the polytrimerization of nitriles in zinc chloride at 400 degrees C produces microporous polymers, higher reaction temperatures induce the formation of additional spherical mesopores with a narrow dispersity. The nitrogen-rich carbonaceous polymer materials thus obtained present surface areas and porosities up to 3300 m(2) g(-1) and 2.4 cm(3) g(-1), respectively. The key point of this synthesis relies on the occurrence of several high temperature polymerization reactions, where irreversible carbonization reactions coupled with the reversible trimerization of nitriles allow the reorganization of the dynamic triazine network. The ZnCl2 molten salt fulfills the requirement of a high temperature solvent, but is also required as catalyst. Thus, this dynamic polymerization system provides not only highly micro- and mesoporous materials, but also allows controlling the pore structure in amorphous organic materials.

Facile and green synthesis of mesoporous Co3O4 nanocubes and their applications for supercapacitors.

PubMed

Liu, Xiangmei; Long, Qing; Jiang, Chunhui; Zhan, Beibei; Li, Chen; Liu, Shujuan; Zhao, Qiang; Huang, Wei; Dong, Xiaochen

2013-07-21

Nanostructured Co3O4 materials attracted significant attention due to their exceptional electrochemical (pseudo-capacitive) properties. However, rigorous preparation conditions are needed to control the size (especially nanosize), morphology and size distribution of the products obtained by conventional methods. Herein, we describe a novel one step shape-controlled synthesis of uniform Co3O4 nanocubes with a size of 50 nm with the existence of mesoporous carbon nanorods (meso-CNRs). In this synthesis process, meso-CNRs not only act as a heat receiver to directly obtain Co3O4 eliminating the high-temperature post-calcination, but also control the morphology of the resulting Co3O4 to form nanocubes with uniform distribution. More strikingly, mesoporous Co3O4 nanocubes are obtained by further thermal treatment. The structure and morphology of the samples were characterized by scanning electron microscopy, transmission electron microscopy and X-ray diffraction. A possible formation mechanism of mesoporous Co3O4 nanocubes is proposed here. Electrochemical tests have revealed that the prepared mesoporous Co3O4 nanocubes demonstrate a remarkable performance in supercapacitor applications due to the porous structure, which endows fast ion and electron transfer.

A high performance flexible all solid state supercapacitor based on the MnO2 sphere coated macro/mesoporous Ni/C electrode and ionic conducting electrolyte.

PubMed

Zhi, Jian; Reiser, Oliver; Wang, Youfu; Hu, Aiguo

2016-06-09

A high contact resistance between the active materials and the current collector, a low ionic conductivity of the gel electrolyte, and an impenetrable electrode structure are the three major barriers which greatly limit the capacitance of MnO2 in solid state supercapacitors. As a potential solution to these problems, in this work we report a novel electrode for solid state supercapacitors, based on a ternary system composed of hierarchical MnO2 spheres as the active material, macroporous Ni foam as gel penetrable skeletons and an ordered mesoporous carbon (OMC) membrane as the charge-transport accelerating layer. By employing butyl-3-methylimidazolium chloride (BMIMCl) modified gels as the ionic conducting electrolyte, the utilization efficiency of MnO2 on the specific capacitance was enhanced up to 88% of the theoretical value, delivering a volumetric capacitance of 81 F cm(-3), which is the highest value among MnO2 based solid state supercapacitors. Moreover, such a flexible device exhibits exceptional volumetric energy and power density (6.6 Wh L(-1) and 549 W L(-1), based on the whole device volume) combined with a small capacity loss of 8.5% after 6000 cycles under twisting. These encouraging findings unambiguously overcome the energy bottleneck of MnO2 in solid state supercapacitors, and open up a new application of macro/mesoporous materials in flexible devices.

Microfluidic immunosensor based on mesoporous silica platform and CMK-3/poly-acrylamide-co-methacrylate of dihydrolipoic acid modified gold electrode for cancer biomarker detection.

PubMed

Regiart, Matías; Fernández-Baldo, Martin A; Villarroel-Rocha, Jhonny; Messina, Germán A; Bertolino, Franco A; Sapag, Karim; Timperman, Aaron T; Raba, Julio

2017-04-22

We report a hybrid glass-poly (dimethylsiloxane) microfluidic immunosensor for epidermal growth factor receptor (EGFR) determination, based on the covalent immobilization of anti-EGFR antibody (anti-EGFR) on amino-functionalized mesoporous silica (AMS) retained in the central channel of a microfluidic device. The synthetized AMS was characterized by N 2 adsorption-desorption isotherm, scanning electron microscopy (SEM), energy dispersive spectrometry (EDS) and infrared spectroscopy. The cancer biomarker was quantified in human serum samples by a direct sandwich immunoassay measuring through a horseradish peroxidase-conjugated anti-EGFR. The enzymatic product was detected at -100 mV by amperometry on a sputtering gold electrode, modified with an ordered mesoporous carbon (CMK-3) in a matrix of poly-acrylamide-co-methacrylate of dihydrolipoic acid (poly(AC-co-MDHLA)) through in situ copolymerization. CMK-3/poly(AC-co-MDHLA)/gold was characterized by cyclic voltammetry, EDS and SEM. The measured current was directly proportional to the level of EGFR in human serum samples. The linear range was from 0.01 ng mL -1 to 50 ng mL -1 . The detection limit was 3.03 pg mL -1 , and the within- and between-assay coefficients of variation were below 5.20%. The microfluidic immunosensor is a very promising device for the diagnosis of several kinds of epithelial origin carcinomas. Copyright © 2017. Published by Elsevier B.V.

A novel three-dimensional large-pore mesoporous carbon matrix as a potential nanovehicle for the fast release of the poorly water-soluble drug, celecoxib.

PubMed

Zhang, Yanzhuo; Wang, Hong; Li, Chuanjun; Sun, Baoxiang; Wang, Yu; Wang, Siling; Gao, Cunqiang

2014-04-01

A novel mesocellular carbon foam (MSU-FC) with a large pore size and a three-dimensional porous structure for the oral delivery of poorly water-soluble drugs was prepared. The goal of this study was to improve in vitro dissolution and in vivo absorption of celecoxib (CEB), a model drug, by means of novel carbon-based nanoparticles prepared from the MSU-FC matrix. The MSU-FC matrix was synthesized by an inverse replica templating method using mesocellular silica template. A solvent immersion/evaporation method was used to load the drug molecules. The drug-loaded nanoparticles were characterized for morphology, surface area, particle size, mesoporous structure, crystallinity, solubility and dissolution. The effect of MSU-FC on cell viability was measured using the MTT conversion assay. Furthermore, the oral bioavailability of CEB-loaded MSU-FC in fasted rats was compared with that of the marketed product. Our results demonstrate that CEB incorporation into the prepared MSU-FC resulted in an approximately 9-fold increase in aqueous solubility in comparison with crystalline CEB. MSU-FC produced accelerated immediate release of CEB in comparison with crystalline CEB (pure CEB powder or marketed formulation) and the drug-loaded conventional mesoporous carbon particles. The relative bioavailability of CEB for CEB-loaded MSU-FC was 172%. In addition, MSU-FC nanoparticles exhibited very low toxicity. The MSU-FC nanomatrix has been shown to be a promising drug delivery vehicle for improving the dissolution and biopharmaceutical characteristics of poorly water-soluble drugs.

Highly Dispersed Nickel-Containing Mesoporous Silica with Superior Stability in Carbon Dioxide Reforming of Methane: The Effect of Anchoring

PubMed Central

Cai, Wenjia; Ye, Lin; Zhang, Li; Ren, Yuanhang; Yue, Bin; Chen, Xueying; He, Heyong

2014-01-01

A series of nickel-containing mesoporous silica samples (Ni-SiO2) with different nickel content (3.1%–13.2%) were synthesized by the evaporation-induced self-assembly method. Their catalytic activity was tested in carbon dioxide reforming of methane. The characterization results revealed that the catalysts, e.g., 6.7%Ni-SiO2, with highly dispersed small nickel particles, exhibited excellent catalytic activity and long-term stability. The metallic nickel particle size was significantly affected by the metal anchoring effect between metallic nickel particles and unreduced nickel ions in the silica matrix. A strong anchoring effect was suggested to account for the remaining of small Ni particle size and the improved catalytic performance. PMID:28788570

Electrocatalytic interface based on novel carbon nanomaterials for advanced electrochemical sensors

DOE PAGES

Zhou, Ming; Guo, Shaojun

2015-07-17

The rapid development of nanoscience and nanotechnology provides new opportunities for the sustainable progress of nanoscale catalysts (i.e., nanocatalysts). The introduction of nanocatalysts into electronic devices implants their novel functions into electronic sensing systems, resulting in the testing of many advanced electrochemical sensors and the fabrication of some highly sensitive, selective, and stable sensing platforms. In this Review, we will summarize recent significant progress on exploring advanced carbon nanomaterials (such as carbon nanotubes, graphene, highly ordered mesoporous carbons, and electron cyclotron resonance sputtered nanocarbon film) as nanoscale electrocatalysts (i.e., nanoelectrocatalysts) for constructing the catalytic nanointerfaces of electronic devices to achievemore » high-sensitivity and high-selectivity electrochemical sensors. Furthermore, different mechanisms for the extraordinary and unique electrocatalytic activities of these carbon nanomaterials will be also highlighted, compared and discussed. An outlook on the future trends and developments in this area will be provided at the end. Notably, to elaborate the nature of carbon nanomaterial, we will mainly focus on the electrocatalysis of single kind of carbon materials rather than their hybrid composite materials. As a result, we expect that advanced carbon nanomaterials with unique electrocatalytic activities will continue to attract increasing research interest and lead to new opportunities in various fields of research.« less

Electrocatalytic interface based on novel carbon nanomaterials for advanced electrochemical sensors

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

Zhou, Ming; Guo, Shaojun

The rapid development of nanoscience and nanotechnology provides new opportunities for the sustainable progress of nanoscale catalysts (i.e., nanocatalysts). The introduction of nanocatalysts into electronic devices implants their novel functions into electronic sensing systems, resulting in the testing of many advanced electrochemical sensors and the fabrication of some highly sensitive, selective, and stable sensing platforms. In this Review, we will summarize recent significant progress on exploring advanced carbon nanomaterials (such as carbon nanotubes, graphene, highly ordered mesoporous carbons, and electron cyclotron resonance sputtered nanocarbon film) as nanoscale electrocatalysts (i.e., nanoelectrocatalysts) for constructing the catalytic nanointerfaces of electronic devices to achievemore » high-sensitivity and high-selectivity electrochemical sensors. Furthermore, different mechanisms for the extraordinary and unique electrocatalytic activities of these carbon nanomaterials will be also highlighted, compared and discussed. An outlook on the future trends and developments in this area will be provided at the end. Notably, to elaborate the nature of carbon nanomaterial, we will mainly focus on the electrocatalysis of single kind of carbon materials rather than their hybrid composite materials. As a result, we expect that advanced carbon nanomaterials with unique electrocatalytic activities will continue to attract increasing research interest and lead to new opportunities in various fields of research.« less

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

PubMed

Pal, Nabanita; Bhaumik, Asim

2013-03-01

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

Engineering 3D bicontinuous hierarchically macro-mesoporous LiFePO4/C nanocomposite for lithium storage with high rate capability and long cycle stability

PubMed Central

Zhang, Qian; Huang, Shao-Zhuan; Jin, Jun; Liu, Jing; Li, Yu; Wang, Hong-En; Chen, Li-Hua; Wang, Bin-Jie; Su, Bao-Lian

2016-01-01

A highly crystalline three dimensional (3D) bicontinuous hierarchically macro-mesoporous LiFePO4/C nanocomposite constructed by nanoparticles in the range of 50~100 nm via a rapid microwave assisted solvothermal process followed by carbon coating have been synthesized as cathode material for high performance lithium-ion batteries. The abundant 3D macropores allow better penetration of electrolyte to promote Li+ diffusion, the mesopores provide more electrochemical reaction sites and the carbon layers outside LiFePO4 nanoparticles increase the electrical conductivity, thus ultimately facilitating reverse reaction of Fe3+ to Fe2+ and alleviating electrode polarization. In addition, the particle size in nanoscale can provide short diffusion lengths for the Li+ intercalation-deintercalation. As a result, the 3D macro-mesoporous nanosized LiFePO4/C electrode exhibits excellent rate capability (129.1 mA h/g at 2 C; 110.9 mA h/g at 10 C) and cycling stability (87.2% capacity retention at 2 C after 1000 cycles, 76.3% at 5 C after 500 cycles and 87.8% at 10 C after 500 cycles, respectively), which are much better than many reported LiFePO4/C structures. Our demonstration here offers the opportunity to develop nanoscaled hierarchically porous LiFePO4/C structures for high performance lithium-ion batteries through microwave assisted solvothermal method. PMID:27181195

Engineering 3D bicontinuous hierarchically macro-mesoporous LiFePO4/C nanocomposite for lithium storage with high rate capability and long cycle stability.

PubMed

Zhang, Qian; Huang, Shao-Zhuan; Jin, Jun; Liu, Jing; Li, Yu; Wang, Hong-En; Chen, Li-Hua; Wang, Bin-Jie; Su, Bao-Lian

2016-05-16

A highly crystalline three dimensional (3D) bicontinuous hierarchically macro-mesoporous LiFePO4/C nanocomposite constructed by nanoparticles in the range of 50~100 nm via a rapid microwave assisted solvothermal process followed by carbon coating have been synthesized as cathode material for high performance lithium-ion batteries. The abundant 3D macropores allow better penetration of electrolyte to promote Li(+) diffusion, the mesopores provide more electrochemical reaction sites and the carbon layers outside LiFePO4 nanoparticles increase the electrical conductivity, thus ultimately facilitating reverse reaction of Fe(3+) to Fe(2+) and alleviating electrode polarization. In addition, the particle size in nanoscale can provide short diffusion lengths for the Li(+) intercalation-deintercalation. As a result, the 3D macro-mesoporous nanosized LiFePO4/C electrode exhibits excellent rate capability (129.1 mA h/g at 2 C; 110.9 mA h/g at 10 C) and cycling stability (87.2% capacity retention at 2 C after 1000 cycles, 76.3% at 5 C after 500 cycles and 87.8% at 10 C after 500 cycles, respectively), which are much better than many reported LiFePO4/C structures. Our demonstration here offers the opportunity to develop nanoscaled hierarchically porous LiFePO4/C structures for high performance lithium-ion batteries through microwave assisted solvothermal method.

Adsorption of SO2 and NO from incineration flue gas onto activated carbon fibers.

PubMed

Liu, Zhen-Shu

2008-11-01

Activated carbon fibers (ACFs) were used to remove SO2 and NO from incineration flue gas. Three types of ACFs in their origin state and after pretreatment with HNO3, NaOH, and KOH were investigated. The removal efficiencies of SO2 and NO were determined experimentally at defined SO2 and NO concentrations and at temperatures of 150, 200 and 260 degrees C. Experimental results indicated that the removal efficiencies of SO2 and NO using the original ACFs were < 56% and < 27%, respectively. All ACFs modified with HNO3, NaOH, and KOH solution could increase the removal efficiencies of SO(2) and NO. The mesopore volumes and functional groups of ACFs are important in determining the removal of SO2 and NO. When the mesopore volumes of the ACFs are insufficient for removing SO2 and NO, the functional groups on the ACFs are not important in determining the removal of SO2 and NO. On the contrary, the effects of the functional groups on the removal of SO2 and NO are more important than the mesopore volumes as the amount of mesopores on the ACFs is sufficient to remove SO2 and NO. Moreover, the removal efficiencies of SO2 and NO were greatest at 200 degrees C. When the inlet concentration of SO2 increased to 600 ppm, the removal efficiency of SO2 increased slightly and the removal efficiency of NO decreased.

Improving the Durability of Methanol Oxidation Reaction Electro-Catalysts Through the Modification of Carbon Architectures

DTIC Science & Technology

2014-01-01

zeolite template was used in conjunction with liquid cyanamide to form a carbon nitride structure with a better 2D mesoporous hexagonal framework, resulting...the core. Both hybrid inorganic–organic polymer networks and 139 zeolitic inorganic–organic polymer electrolyte materials were used to impregnate an

Preparation of mesoporous carbon nitride structure by the dealloying of Ni/a-CN nanocomposite films

NASA Astrophysics Data System (ADS)

Zhou, Han; Shen, Yongqing; Huang, Jie; Liao, Bin; Wu, Xianying; Zhang, Xu

2018-05-01

The preparation of mesoporous carbon nitride (p-CN) structure by the selective dealloying process of Ni/a-CN nanocomposite films is investigated. The composition and structure of the Ni/a-CN nanocomposite films and porous carbon nitride (p-CN) films are determined by scan electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. Phase separated structure including nickel carbide phase and the surrounding amorphous carbon nitride (a-CN) matrix are detected for the as-deposited films. Though the bulk diffusion is introduced in the film during the annealing process, the grain sizes for the post-annealed films are around 10 nm and change little comparing with the ones of the as-deposited films, which is associated with the thermostability of the CN surrounding in the film. The p-CN skeleton with its pore size around 12.5 nm is formed by etching the post-annealed films, indicative of the stability of the phase separated structure during the annealing process.

Self-Volatilization Approach to Mesoporous Carbon Nanotube/Silver Nanoparticle Hybrids: The Role of Silver in Boosting Li Ion Storage.

PubMed

Jiang, Hao; Zhang, Haoxuan; Fu, Yao; Guo, Shaojun; Hu, Yanjie; Zhang, Ling; Liu, Yu; Liu, Honglai; Li, Chunzhong

2016-01-26

One of the biggest challenging issues of carbon nanomaterials for Li ion batteries (LIBs) is that they show low initial Coulombic efficiency (CE), leading to a limited specific capacity. Herein, we demonstrate a simple template self-volatilization strategy for in situ synthesis of mesoporous carbon nanotube/Ag nanoparticle (NP) hybrids (Ag-MCNTs) to boost the LIBs' performance. The key concept of Ag-MCNTs for enhancing LIBs is that a small trace of Ag NPs on MCNTS can greatly restrict the formation of a thicker solid electrolyte interphase film, which has been well verified by both transmission electron microscopy results and quantum density functional theory calculations, leading to the highest initial CE in all the reported carbon nanomaterials. This uncovered property of Ag NPs from Ag-MCNTs makes them exhibit a very high reversible capacity of 1637 mAh g(-1) after 400 discharge/charge cycles at 100 mA g(-1), approximately 5 times higher than the theoretical value of a graphite anode (372 mAh g(-1)), excellent rate capability, and long cycle life.

Template-directed assembly of metal-chalcogenide nanocrystals into ordered mesoporous networks.

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

Vamvasakis, Ioannis; Subrahmanyam, Kota S.; Kanatzidis, Mercouri G.

Although great progress in the synthesis of porous networks of metal and metal oxide nanoparticles with highly accessible pore surface and ordered mesoscale pores has been achieved, synthesis of assembled 3D mesostructures of metal-chalcogenide nanocrystals is still challenging. In this work we demonstrate that ordered mesoporous networks, which comprise well-defined interconnected metal sulfide nanocrystals, can be prepared through a polymer-templated oxidative polymerization process. The resulting self-assembled mesostructures that were obtained after solvent extraction of the polymer template impart the unique combination of light-emitting metal chalcogenide nanocrystals, three-dimensional open-pore structure, high surface area, and uniform pores. We show that the poremore » surface of these materials is active and accessible to incoming molecules, exhibiting high photocatalytic activity and stability, for instance, in oxidation of 1-phenylethanol into acetophenone. We demonstrate through appropriate selection of the synthetic components that this method is general to prepare ordered mesoporous materials from metal chalcogenide nanocrystals with various sizes and compositions.« less

Phosphorous and nitrogen dual heteroatom doped mesoporous carbon synthesized via microwave method for supercapacitor application

NASA Astrophysics Data System (ADS)

Nasini, Udaya B.; Bairi, Venu Gopal; Ramasahayam, Sunil Kumar; Bourdo, Shawn E.; Viswanathan, Tito; Shaikh, Ali U.

2014-03-01

Phosphorus (P) and nitrogen (N) dual heteroatom doped mesoporous carbon (PNDC) synthesized by microwave assisted carbonization of tannin cross-linked to melamine in the presence of polyphosphoric acid was evaluated electrochemically for supercapacitor application. Controlling the N content by varying the amount of tannin to melamine in the carbonization process produced varying nitrogen, phosphorus and oxygen functionalities along with different physical properties. Electrochemical characterization studies revealed that N content is responsible for pseudocapacitance and high surface area plays a vital role in improving the capacitative behavior by enhanced electric double layer formation. In 1.0 M H2SO4 and 6.0 M KOH, PNDC-2 showed a high specific capacitance of 271 F g-1 and 236 F g-1, respectively. XPS results demonstrate the presence of pyridinic-N, quaternary-N as well as quinone type oxygen functionalities, which accounts for redox reactions and likely play an important role in the transportation of electrons during the charge/discharge process. Thus, the microwave assisted synthesis of doped carbon can provide a novel method of synthesizing materials useful for the fabrication of cheap and high performance supercapacitors.

Phenolic resin-based porous carbons for adsorption and energy storage applications

NASA Astrophysics Data System (ADS)

Wickramaratne, Nilantha P.

The main objective of this dissertation research is to develop phenolic resin based carbon materials for range of applications by soft-templating and Stober-like synthesis strategies. Applications Studied in this dissertation are adsorption of CO2, bio-molecular and heavy metal ions, and energy storage devices. Based on that, our goal is to design carbon materials with desired pore structure, high surface area, graphitic domains, incorporated metal nanoparticles, and specific organic groups and heteroatoms. In this dissertation the organic-organic self-assembly of phenolic resins and triblock copolymers under acidic conditions will be used to obtain mesoporous carbons/carbon composites and Stober-like synthesis involving phenolic resins under basic condition will be used to prepare polymer/carbon particles and their composites. The structure of this dissertation consists of an introductory chapter (Chapter 1) discussing the general synthesis of carbon materials, particularly the soft-templating strategy and Stober-like carbon synthesis. Also, Chapter 1 includes a brief outline of applications namely adsorption of CO2, biomolecule and heavy metal ions, and supercapacitors. Chapter 2 discusses the techniques used for characterization of the carbon materials studied. This chapter starts with nitrogen adsorption analysis, which is used to measure the specific surface area, pore volume, distribution of pore sizes, and pore width. In addition to nitrogen adsorption, powder X-ray diffraction (XRD), transmission electron microscopy (TEM), high resolution thermogravimetric analysis (HR-TGA), cyclic voltammetry (CV) and CHNS elemental analysis (EA) are mentioned too. Chapter 3 is focused on carbon materials for CO2 adsorption. There are different types of porous solid materials such as silicate, MOFs, carbons, and zeolites studied for CO2 adsorption. However, the carbon based materials are considered to be the best candidates for CO 2 adsorption to the industrial point of view. So far, carbons with high surface area and nitrogen content have been vastly studied. Also, there are several reports showing the importance of pore size towards CO2 adsorption at ambient conditions. In the case of nitrogen containing carbons, it was shown that the incorporation of nitrogen into carbon matrix is a challenging task. In chapter 3, we discussed how to improve the surface area and pore size distribution of phenolic resin-based carbons to obtain optimum CO 2 adsorption capacities at ambient conditions. The chemical and physical activation of polymer/carbon particles is used to generate necessary physical properties of the final carbons, which display unprecedented CO2 adsorption capacities at ambient conditions. Moreover, the modified Stober-like methods are used for the synthesis of nitrogen containing carbon particles. These facile synthesis methods afford highly porous nitrogen containing carbons with comparatively high CO2 adsorption capacities at ambient conditions. Chapter 4 begins with synthesis of ultra large mesoporous carbons using (ethylene oxide)38 (butylene oxide)46 (ethylene oxide) 38 triblock copolymer as a soft template and phenolic resins as the carbon precursors. Even though, there are many reports dealing with the synthesis of mesoporous silica with large pores for bio-molucular adsorption their high cost discourage them to use in industrial applications. However, cheap mesoporous carbons with large pores (>15 nm) are potential materials for bio-molecular adsorption on large scale. The first part of chapter 4 is demonstrates the synthesis of mesoporous carbons with ultra large pores for bio-molecular adsorption. Lysozyme was selected as a model biomolecule for adsorption processes. The second part of Chapter 4 is focused on functionalized polymer spheres for heavy metal ions adsorption. It is shown that the synthesis of functionalized polymer spheres can be achieved by using modified Stober method; the reacting spheres show very high Cu2+ ion adsorption capacities. Next, Chapter 5 is devoted to carbon materials for supercapacitors. There are mainly two types of electrochemical capacitors namely EDLC and pseudocapacitors. In EDLC, the energy is stored due to electrochemical attraction between electrode and electrolyte interface. To store more ionic charges on to the carbon electrode, it is essential to have high surface area carbon materials. In the case of pseudocapacitors, the energy is stored due to the redox reaction taking place at the electrode and electrolyte interface. Moreover, conductivity of the electrode is also important for the construction of superior electrode materials. To address these vital issues, the electrode materials has been prepared with special emphasis on the enhancement of their surface area to attract more charges at the electrode-electrolyte interface, introducing graphitic moieties to the carbon matrix to improve the conductivity and doping carbons with metal/heteroatoms to improve both capacitance through pseudocapacitive and conductivity.

Magnetic porous Fe3O4/carbon octahedra derived from iron-based metal-organic framework as heterogeneous Fenton-like catalyst

NASA Astrophysics Data System (ADS)

Li, Wenhui; Wu, Xiaofeng; Li, Shuangde; Tang, Wenxiang; Chen, Yunfa

2018-04-01

The synthesis of effective and recyclable Fenton-like catalyst is still a key factor for advanced oxidation processes. Herein, magnetic porous Fe3O4/carbon octahedra were constructed by a two-step controlled calcination of iron-based metal organic framework. The porous octahedra were assembled by interpenetrated Fe3O4 nanoparticles coated with graphitic carbon layer, offering abundant mesoporous channels for the solid-liquid contact. Moreover, the oxygen-containing functional groups on the surface of graphitic carbon endow the catalysts with hydrophilic nature and well-dispersion into water. The porous Fe3O4/carbon octahedra show efficiently heterogeneous Fenton-like reactions for decomposing the organic dye methylene blue (MB) with the help of H2O2, and nearly 100% removal efficiency within 60 min. Furthermore, the magnetic catalyst retains the activity after ten cycles and can be easily separated by external magnetic field, indicating the long-term catalytic durability and recyclability. The good Fenton-like catalytic performance of the as-synthesized Fe3O4/carbon octahedra is ascribed to the unique mesoporous structure derived from MOF-framework, as well as the sacrificial role and stabilizing effect of graphitic carbon layer. This work provides a facile strategy for the controllable synthesis of integrated porous octahedral structure with graphitic carbon layer, and thereby the catalyst holds significant potential for wastewater treatment.

High Capacitive Storage Performance of Sulfur and Nitrogen Codoped Mesoporous Graphene.

PubMed

Ma, Xinlong; Gao, Daowei

2018-03-22

Mesoporous graphene is synthesized based on the chemical vapor deposition methodology by using heavy MgO flakes as substrates in a fluidized-bed reactor. Subsequently, sulfur and nitrogen coincorporation into graphene frameworks is realized by the reaction between carbon atoms and thiourea molecules. The as-obtained sulfur and nitrogen codoped mesoporous graphene (SNMG) exhibits remarkable capacitive energy-storage behavior, as a result of well-developed pore channels, in terms of that in a symmetric supercapacitor and lithium-ion hybrid capacitor (LIHC). The ultrahigh durability of the SNMG/SNMG symmetric supercapacitor is demonstrated by long-term cycling, for which no capacitance decay is found after 20 000 cycles. A LIHC constructed from commercial Li 4 Ti 5 O 12 (LTO) as the anode and SNMG as the cathode is capable of delivering much enhanced lithium-storage ability and better rate capability than that of activated carbon (AC)/LTO LIHC. Moreover, SNMG/LTO LIHC exhibits maximum energy and power densities of 86.2 Wh kg -1 and 7443 W kg -1 and maintains 87 % capacitance retention after 2000 cycles. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Luminescent properties and energy transfer of luminescent carbon dots assembled mesoporous Al(2)O(3): Eu(3) co-doped materials for temperature sensing.

PubMed

He, Youling; He, Jiangling; Zhang, Haoran; Liu, Yingliang; Lei, Bingfu

2017-06-15

Owning to the hydrogen-band interactions, blue-light-emitting luminescent carbon dots (CDs) synthesized by one-pot hydrothermal treatment were successfully assembled into Eu 3+ doped mesoporous aluminas (MAs). Interesting, dual-emissive CDs/MAs co-doped materials with higher quantum yield (QY), long-term stability, mesoporous structure, high thermal stability, and large surface areas were obtained. Furthermore, the obtained CDs/MAs co-doped materials possessed tunable color, and excellent temperature sensitivity due to the existing of energy transfer between CDs and Eu 3+ ion. The energy transfer efficiency (η) and energy transfer probability (P) for CDs/Eu 3+ co-doped materials possessed a monotonous tendency with the change of Eu 3+ content. More importantly, the dual-emissive colors can be regularly adjusted through regulating their excitation wavelength or relative mass ratio. In addition, the emission intensity of the CDs/MAs co-doped materials gradually decreased with increasing temperature showing the clear temperature dependence, this dual-emissive thermometer was with high sensitivity, owning a great fitted curve in the range from 100 to 360K under a single wavelength excitation. Copyright © 2017 Elsevier Inc. All rights reserved.

Mesoporous nanostructured Nb-doped titanium dioxide microsphere catalyst supports for PEM fuel cell electrodes.

PubMed

Chevallier, Laure; Bauer, Alexander; Cavaliere, Sara; Hui, Rob; Rozière, Jacques; Jones, Deborah J

2012-03-01

Crystalline microspheres of Nb-doped TiO(2) with a high specific surface area were synthesized using a templating method exploiting ionic interactions between nascent inorganic components and an ionomer template. The microspheres exhibit a porosity gradient, with a meso-macroporous kernel, and a mesoporous shell. The material has been investigated as cathode electrocatalyst support for polymer electrolyte membrane (PEM) fuel cells. A uniform dispersion of Pt particles on the Nb-doped TiO(2) support was obtained using a microwave method, and the electrochemical properties assessed by cyclic voltammetry. Nb-TiO(2) supported Pt demonstrated very high stability, as after 1000 voltammetric cycles, 85% of the electroactive Pt area remained compared to 47% in the case of commercial Pt on carbon. For the oxygen reduction reaction (ORR), which takes place at the cathode, the highest stability was again obtained with the Nb-doped titania-based material even though the mass activity calculated at 0.9 V vs RHE was slightly lower. The microspherical structured and mesoporous Nb-doped TiO(2) is an alternative support to carbon for PEM fuel cells. © 2012 American Chemical Society

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

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

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

2006-07-15

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

Synthesis of mesoporous SAPO-34 molecular sieves and their applications in dehydration of butanols and ethanol.

PubMed

Jun, Jong Won; Jeon, Jaewoo; Kim, Chul-Ung; Jeong, Kwang-Eun; Jeong, Soon-Yong; Jhung, Sung Hwa

2013-04-01

Microporous SAPO-34 molecular sieves were hydrothermally synthesized with microwave irradiation in the presence of tetraethylammonium hydroxide (TEAOH) as a template. SAPO-34 molecular sieves with mesoporosity were also prepared in the presence of carbon black as a hard template. By increasing the content of the carbon black template in the synthesis, the mesopore volume increased. Dehydration of alcohols (butanols and ethanol) was carried out with the synthesized SAPO-34 molecular sieves, and the lifetime of the catalysts for the dehydration reaction increased as the mesoporosity increased. Moreover, the performance of the microporous catalyst synthesized with microwave was better than that of the catalyst obtained with conventional electric heating. The relative performance of the catalytic dehydration may be explained by the mesoporosity and the crystal size. Therefore, it may be concluded that small-sized SAPO-34 molecular sieves with high mesoporosity can be produced efficiently with microwave irradiation in the presence of carbon black template, and the molecular sieves are effective in the stable dehydration of alcohols.

Erythrocyte-like hollow carbon capsules and their application in proton exchange membrane fuel cells.

PubMed

Kim, Jung Ho; Yu, Jong-Sung

2010-12-14

Hierarchical nanostructured erythrocyte-like hollow carbon (EHC) with a hollow hemispherical macroporous core of ca. 230 nm in diameter and 30-40 nm thick mesoporous shell was synthesized and explored as a cathode catalyst support in a proton exchange membrane fuel cell (PEMFC). The morphology control of EHC was successfully achieved using solid core/mesoporous shell (SCMS) silica template and different styrene/furfuryl alcohol mixture compositions by a nanocasting method. The EHC-supported Pt (20 wt%) cathodes prepared have demonstrated markedly enhanced catalytic activity towards oxygen reduction reactions (ORRs) and greatly improved PEMFC polarization performance compared to carbon black Vulcan XC-72 (VC)-supported ones, probably due to the superb structural characteristics of the EHC such as uniform size, well-developed porosity, large specific surface area and pore volume. In particular, Pt/EHC cathodes exhibited ca. 30-60% higher ORR activity than a commercial Johnson Matthey Pt catalyst at a low catalyst loading of 0.2 mg Pt cm(-2).

Top-Down Strategy to Synthesize Mesoporous Dual Carbon Armored MnO Nanoparticles for Lithium-Ion Battery Anodes.

PubMed

Zhang, Wei; Li, Jiannian; Zhang, Jie; Sheng, Jinzhi; He, Ting; Tian, Meiyue; Zhao, Yufeng; Xie, Changjun; Mai, Liqiang; Mu, Shichun

2017-04-12

To overcome inferior rate capability and cycle stability of MnO-based materials as a lithium-ion battery anode associated with the pulverization and gradual aggregation during the conversion process, we constructed robust mesoporous N-doped carbon (N-C) protected MnO nanoparticles on reduced graphene oxide (rGO) (MnO@N-C/rGO) by a simple top-down incorporation strategy. Such dual carbon protection endows MnO@N-C/rGO with excellent structural stability and enhanced charge transfer kinetics. At 100 mA g -1 , it exhibits superior rate capability as high as 864.7 mAh g -1 , undergoing the deep charge/discharge for 70 cycles and outstanding cyclic stability (after 1300 cyclic tests at 2000 mA g -1 ; 425.0 mAh g -1 remains, accompanying merely 0.004% capacity decay per cycle). This facile method provides a novel strategy for synthesis of porous electrodes by making use of highly insulating materials.

Thermal decomposition pathway of undoped and doped zinc layered gallate nanohybrid with Fe 3+, Co 2+ and Ni 2+ to produce mesoporous and high pore volume carbon material

NASA Astrophysics Data System (ADS)

Ghotbi, Mohammad Yeganeh; bin Hussein, Mohd Zobir; Yahaya, Asmah Hj; Abd Rahman, Mohd Zaki

2009-12-01

A series of brucite-like materials, undoped and doped zinc layered hydroxide nitrate with 2% (molar) Fe 3+, Co 2+ and Ni 2+ were synthesized. Organic-inorganic nanohybrid material with gallate anion as a guest, and zinc hydroxide nitrate, as an inorganic layered host was prepared by the ion-exchange method. The nanohybrid materials were heat-treated at various temperatures, 400-700 °C. X-ray diffraction, thermal analysis and also Fourier transform infrared results showed that incorporation of the doping agents within the zinc layered hydroxide salt layers has enhanced the heat-resistivity of the nanohybrid materials in the thermal decomposition pathway. Porous carbon materials can be obtained from the heat-treating the nanohybrids at 600 and 700 °C. Calcination of the nanohybrids at 700 °C under nitrogen atmosphere produces mesoporous and high pore volume carbon materials.

Immobilization of Bacillus sp. in mesoporous activated carbon for degradation of sulphonated phenolic compound in wastewater.

PubMed

Sekaran, G; Karthikeyan, S; Gupta, V K; Boopathy, R; Maharaja, P

2013-03-01

Xenobiotic compounds are used in considerable quantities in leather industries besides natural organic and inorganic compounds. These compounds resist biological degradation and thus they remain in the treated wastewater in the unaltered molecular configurations. Immobilization of organisms in carrier matrices protects them from shock load application and from the toxicity of chemicals in bulk liquid phase. Mesoporous activated carbon (MAC) has been considered in the present study as the carrier matrix for the immobilization of Bacillus sp. isolated from Effluent Treatment Plant (ETP) employed for the treatment of wastewater containing sulphonated phenolic (SP) compounds. Temperature, pH, concentration, particle size and mass of MAC were observed to influence the immobilization behavior of Bacillus sp. The percentage immobilization of Bacillus sp. was the maximum at pH 7.0, temperature 20 °C and at particle size 300 μm. Enthalpy, free energy and entropy of immobilization were -46.9 kJ mol(-1), -1.19 kJ mol(-1) and -161.36 JK(-1)mol(-1) respectively at pH 7.0, temperature 20 °C and particle size 300 μm. Higher values of ΔH(0) indicate the firm bonding of the Bacillus sp. in MAC. Degradation of aqueous sulphonated phenolic compound by Bacillus sp. immobilized in MAC followed pseudo first order rate kinetics with rate constant 1.12 × 10(-2) min(-1). Copyright © 2012 Elsevier B.V. All rights reserved.

Mercerized mesoporous date pit activated carbon-A novel adsorbent to sequester potentially toxic divalent heavy metals from water.

PubMed

Aldawsari, Abdullah; Khan, Moonis Ali; Hameed, B H; Alqadami, Ayoub Abdullah; Siddiqui, Masoom Raza; Alothman, Zeid Abdullah; Ahmed, A Yacine Badjah Hadj

2017-01-01

A substantive approach converting waste date pits to mercerized mesoporous date pit activated carbon (DPAC) and utilizing it in the removal of Cd(II), Cu(II), Pb(II), and Zn(II) was reported. In general, rapid heavy metals adsorption kinetics for Co range: 25-100 mg/L was observed, accomplishing 77-97% adsorption within 15 min, finally, attaining equilibrium in 360 min. Linear and non-linear isotherm studies revealed Langmuir model applicability for Cd(II) and Pb(II) adsorption, while Freundlich model was fitted to Zn(II) and Cu(II) adsorption. Maximum monolayer adsorption capacities (qm) for Cd(II), Pb(II), Cu(II), and Zn(II) obtained by non-linear isotherm model at 298 K were 212.1, 133.5, 194.4, and 111 mg/g, respectively. Kinetics modeling parameters showed the applicability of pseudo-second-order model. The activation energy (Ea) magnitude revealed physical nature of adsorption. Maximum elution of Cu(II) (81.6%), Zn(II) (70.1%), Pb(II) (96%), and Cd(II) (78.2%) were observed with 0.1 M HCl. Thermogravimetric analysis of DPAC showed a total weight loss (in two-stages) of 28.3%. Infra-red spectral analysis showed the presence of carboxyl and hydroxyl groups over DPAC surface. The peaks at 820, 825, 845 and 885 cm-1 attributed to Zn-O, Pb-O, Cd-O, and Cu-O appeared on heavy metals saturated DPAC, confirmed their binding on DPAC during the adsorption.

Physical state of poorly water soluble therapeutic molecules loaded into SBA-15 ordered mesoporous silica carriers: a case study with itraconazole and ibuprofen.

PubMed

Mellaerts, Randy; Jammaer, Jasper A G; Van Speybroeck, Michiel; Chen, Hong; Van Humbeeck, Jan; Augustijns, Patrick; Van den Mooter, Guy; Martens, Johan A

2008-08-19

The ordered mesoporous silica material SBA-15 was loaded with the model drugs itraconazole and ibuprofen using three different procedures: (i) adsorption from solution, (ii) incipient wetness impregnation, and (iii) heating of a mixture of drug and SBA-15 powder. The location of the drug molecules in the SBA-15 particles and molecular interactions were investigated using nitrogen adsorption, TGA, DSC, DRS UV-vis, and XPS. The in vitro release of hydrophobic model drugs was evaluated in an aqueous environment simulating gastric fluid. The effectiveness of the loading method was found to be strongly compound dependent. Incipient wetness impregnation using a concentrated itraconazole solution in dichloromethane followed by solvent evaporation was most efficient for dispersing itraconazole in SBA-15. The itraconazole molecules were located on the mesopore walls and inside micropores of the mesopore walls. When SBA-15 was loaded by slurrying it in a diluted itraconazole solution from which the solvent was evaporated, the itraconazole molecules ended up in the mesopores that they plugged locally. At a loading of 30 wt %, itraconazole exhibited intermolecular interactions inside the mesopores revealed by UV spectroscopy and endothermic events traced with DSC. The physical mixing of itraconazole and SBA-15 powder followed by heating above the itraconazole melting temperature resulted in formulations in which glassy itraconazole particles were deposited externally on the SBA-15 particles. Loading with ibuprofen was successful with each of the three loading procedures. Ibuprofen preferably is positioned inside the micropores. In vitro release experiments showed fast release kinetics provided the drug molecules were evenly deposited over the mesoporous surface.

Preparation of highly ordered mesoporous Al2O3/TiO2 and its application in dye-sensitized solar cells.

PubMed

Kim, Jae-Yup; Kang, Soon Hyung; Kim, Hyun Sik; Sung, Yung-Eun

2010-02-16

Highly ordered mesoporous Al(2)O(3)/TiO(2) was prepared by sol-gel reaction and evaporation-induced self-assembly (EISA) for use in dye-sensitized solar cells. The prepared materials had two-dimensional, hexagonal pore structures with anatase crystalline phases. The average pore size of mesoporous Al(2)O(3)/TiO(2) remained uniform and in the range of 6.33-6.58 nm while the Brunauer-Emmett-Teller (BET) surface area varied from 181 to 212 m(2)/g with increasing the content of Al(2)O(3). The incorporation of Al content retarded crystallite growth, thereby decreasing crystallite size while simultaneously improving the uniformity of pore size and volume. The thin Al(2)O(3) layer was located mostly on the mesopore surface, as confirmed by X-ray photoelectron spectroscopy (XPS). The Al(2)O(3) coating on the mesoporous TiO(2) film contributes to the essential energy barrier which blocks the charge recombination process in dye-sensitized solar cells. Mesoporous Al(2)O(3)/TiO(2) (1 mol % Al(2)O(3)) exhibited enhanced power conversion efficiency (V(oc) = 0.74 V, J(sc) = 15.31 mA/cm(2), fill factor = 57%, efficiency = 6.50%) compared to pure mesoporous TiO(2) (V(oc) = 0.72 V, J(sc) = 16.03 mA/cm(2), fill factor = 51%, efficiency = 5.88%). Therefore, the power conversion efficiency was improved by approximately 10.5%. In particular, the increase in V(oc) and fill factor resulted from the inhibition of charge recombination and the improvement of pore structure.

Adsorption of aromatic compounds by carbonaceous adsorbents: a comparative study on granular activated carbon, activated carbon fiber, and carbon nanotubes.

PubMed

Zhang, Shujuan; Shao, Ting; Kose, H Selcen; Karanfil, Tanju

2010-08-15

Adsorption of three aromatic organic compounds (AOCs) by four types of carbonaceous adsorbents [a granular activated carbon (HD4000), an activated carbon fiber (ACF10), two single-walled carbon nanotubes (SWNT, SWNT-HT), and a multiwalled carbon nanotube (MWNT)] with different structural characteristics but similar surface polarities was examined in aqueous solutions. Isotherm results demonstrated the importance of molecular sieving and micropore effects in the adsorption of AOCs by carbonaceous porous adsorbents. In the absence of the molecular sieving effect, a linear relationship was found between the adsorption capacities of AOCs and the surface areas of adsorbents, independent of the type of adsorbent. On the other hand, the pore volume occupancies of the adsorbents followed the order of ACF10 > HD4000 > SWNT > MWNT, indicating that the availability of adsorption site was related to the pore size distributions of the adsorbents. ACF10 and HD4000 with higher microporous volumes exhibited higher adsorption affinities to low molecular weight AOCs than SWNT and MWNT with higher mesopore and macropore volumes. Due to their larger pore sizes, SWNTs and MWNTs are expected to be more efficient in adsorption of large size molecules. Removal of surface oxygen-containing functional groups from the SWNT enhanced adsorption of AOCs.

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

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

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

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

Iron-Induced Activation of Ordered Mesoporous Nickel Cobalt Oxide Electrocatalyst for the Oxygen Evolution Reaction.

PubMed

Deng, Xiaohui; Öztürk, Secil; Weidenthaler, Claudia; Tüysüz, Harun

2017-06-28

Herein, ordered mesoporous nickel cobalt oxides prepared by the nanocasting route are reported as highly active oxygen evolution reaction (OER) catalysts. By using the ordered mesoporous structure as a model system and afterward elevating the optimal catalysts composition, it is shown that, with a simple electrochemical activation step, the performance of nickel cobalt oxide can be significantly enhanced. The electrochemical impedance spectroscopy results indicated that charge transfer resistance increases for Co 3 O 4 spinel after an activation process, while this value drops for NiO and especially for CoNi mixed oxide significantly, which confirms the improvement of oxygen evolution kinetics. The catalyst with the optimal composition (Co/Ni 4/1) reaches a current density of 10 mA/cm 2 with an overpotential of a mere 336 mV and a Tafel slope of 36 mV/dec, outperforming benchmarked and other reported Ni/Co-based OER electrocatalysts. The catalyst also demonstrates outstanding durability for 14 h and maintained the ordered mesoporous structure. The cyclic voltammograms along with the electrochemical measurements in Fe-free KOH electrolyte suggest that the activity boost is attributed to the generation of surface Ni(OH) 2 species that incorporate Fe impurities from the electrolyte. The incorporation of Fe into the structure is also confirmed by inductively coupled plasma optical emission spectrometry.

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

NASA Astrophysics Data System (ADS)

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

2007-12-01

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

Mesoporous Aluminosilicates as a Host and Reactor for Preparation of Ordered Metal Nanowires

NASA Astrophysics Data System (ADS)

Eliseev, A. A.; Napolskii, K. S.; Kolesnik, I. V.; Kolenko, Yu. V.; Lukashin, A. V.; Gornert, P.; Tretyakov, Yu. D.

The creation of functional nanomaterials with the controlled properties is emerging as a new area of great technological and scientific interest, in particular, it is a key technology for developing novel high-density data storage devices. Today, no other technology can compete with magnetic carriers in information storage density and access rate. However, usually very small (10-1000 nm3) magnetic nanoparticles shows para- or superparamagnetic properties, with very low blocking temperatures and no coercitivity at normal conditions. One possible solution of this problem is preparation of highly anisotropic nanostructures. From the other hand, the use of purely nanocrystalline systems is limited because of their low stability and tendency to form aggregates. These problems could be solved by encapsulation of nanoparticles to a chemically inert matrix. One of the promising matrices for preparation of highly anisotropic magnetic nanoparticles is mesoporous silica or mesoporous aluminosilicates. Mesoporous silica is an amorphous SiO2 with a highly ordered uniform pore structure (the pore diameter can be controllably varied from 2 to 50 nm). This pore system is a perfect reactor for synthesis of nanocomposites due to the limitation of reaction zone by the pore walls. One could expect that size and shape of nanoparticles incorporated into mesoporous silica to be consistent with the dimensions of the porous framework.

CO₂ adsorption on amine-functionalized periodic mesoporous benzenesilicas.

PubMed

Sim, Kyohyun; Lee, Nakwon; Kim, Joonseok; Cho, Eun-Bum; Gunathilake, Chamila; Jaroniec, Mietek

2015-04-01

CO2 adsorption was investigated on amine-functionalized mesoporous silica (SBA-15) and periodic mesoporous organosilica (PMO) samples. Hexagonally (p6mm) ordered mesoporous SBA-15 and benzene-PMO (BPMO) samples were prepared in the presence of Pluronic P123 block copolymer template under acidic conditions. Three kinds of amine-containing organosilanes and polyethylenimine were used to functionalize SBA-15 and BPMO. Small-angle X-ray scattering and nitrogen adsorption isotherms showed that these samples featured ordered mesostructure, high surface area, and narrow pore size distributions. Solid-state (13)C- and (29)Si cross-polarization magic-angle spinning NMR spectra showed chemical linkage between amine-containing modifiers and the surface of mesoporous materials. The chemically linked amine-containing modifiers were found to be on both the inner and outer surfaces. N-[3-(trimethoxysilyl)propyl]ethylenediamine-modified BPMO (A2-BPMO) sample exhibited the highest CO2 uptake (i.e., ∼3.03 mmol/g measured on a volumetric adsorption analyzer) and the fastest adsorption rate (i.e., ∼13 min to attain 90% of the maximum amount) among all the samples studied. Selectivity and reproducibility measurements for the A2-BPMO sample showed quite good performance in flowing N2 gas at 40 mL/min and CO2 gas of 60 mL/min at 25 °C.

Effects of adding ethanol to KOH electrolyte on electrochemical performance of titanium carbide-derived carbon

NASA Astrophysics Data System (ADS)

Xu, Jiang; Zhang, Ruijun; Chen, Peng; Ge, Shanhai

2014-01-01

Porous carbide-derived carbons (CDCs) are synthesized from TiC at different chlorination temperatures as electrode materials for electrochemical capacitors. It is found that the microstructure of the produced CDCs has significant influence on both the hydrophilicity in aqueous KOH electrolyte and the resultant electrochemical performance. Because the TiC-CDC synthesized at higher temperature (e.g. 1000 °C) contains well-ordered graphite ribbons, it shows lower hydrophilicity and specific capacitance. It is also found that addition of a small amount of ethanol to KOH electrolyte effectively improves the wettability of the CDCs synthesized at higher temperature and the corresponding specific capacitance. Compared with the CDC synthesized at 600 °C, the CDC synthesized at 1000 °C shows fast ion transport and excellent capacitive behavior in KOH electrolyte with addition of ethanol because of the existences of mesopores and high specific surface area.

Cellular membrane trafficking of mesoporous silica nanoparticles

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

Fang, I-Ju

This dissertation mainly focuses on the investigation of the cellular membrane trafficking of mesoporous silica nanoparticles. We are interested in the study of endocytosis and exocytosis behaviors of mesoporous silica nanoparticles with desired surface functionality. The relationship between mesoporous silica nanoparticles and membrane trafficking of cells, either cancerous cells or normal cells was examined. Since mesoporous silica nanoparticles were applied in many drug delivery cases, the endocytotic efficiency of mesoporous silica nanoparticles needs to be investigated in more details in order to design the cellular drug delivery system in the controlled way. It is well known that cells can engulfmore » some molecules outside of the cells through a receptor-ligand associated endocytosis. We are interested to determine if those biomolecules binding to cell surface receptors can be utilized on mesoporous silica nanoparticle materials to improve the uptake efficiency or govern the mechanism of endocytosis of mesoporous silica nanoparticles. Arginine-glycine-aspartate (RGD) is a small peptide recognized by cell integrin receptors and it was reported that avidin internalization was highly promoted by tumor lectin. Both RGD and avidin were linked to the surface of mesoporous silica nanoparticle materials to investigate the effect of receptor-associated biomolecule on cellular endocytosis efficiency. The effect of ligand types, ligand conformation and ligand density were discussed in Chapter 2 and 3. Furthermore, the exocytosis of mesoporous silica nanoparticles is very attractive for biological applications. The cellular protein sequestration study of mesoporous silica nanoparticles was examined for further information of the intracellular pathway of endocytosed mesoporous silica nanoparticle materials. The surface functionality of mesoporous silica nanoparticle materials demonstrated selectivity among the materials and cancer and normal cell lines. We aimed to determine the specific organelle that mesoporous silica nanoparticles could approach via the identification of harvested proteins from exocytosis process. Based on the study of endo- and exocytosis behavior of mesoporous silica nanoparticle materials, we can design smarter drug delivery vehicles for cancer therapy that can be effectively controlled. The destination, uptake efficiency and the cellular distribution of mesoporous silica nanoparticle materials can be programmable. As a result, release mechanism and release rate of drug delivery systems can be a well-controlled process. The deep investigation of an endo- and exocytosis study of mesoporous silica nanoparticle materials promotes the development of drug delivery applications.« less

A novel strategy to design sustained-release poorly water-soluble drug mesoporous silica microparticles based on supercritical fluid technique.

PubMed

Li-Hong, Wang; Xin, Che; Hui, Xu; Li-Li, Zhou; Jing, Han; Mei-Juan, Zou; Jie, Liu; Yi, Liu; Jin-Wen, Liu; Wei, Zhang; Gang, Cheng

2013-09-15

The organic solvent solution immersion method was often used to achieve the loading of the drugs into mesoporous silica, but the drugs that have loaded into the pores of the mesoporous silica would inevitable migrate from the inside to the external surface or near the outside surface during the process of drying. Hence, it often leads to the pores of mesoporous materials not be fully utilized, and results in a low drug loading efficiency and a fast releasing rate. The purpose of this study was to develop a novel drug loading strategy to avoid soluble component migration during the process of drying, then, to prepare poorly water-soluble drug mesoporous silica microparticles with higher drug loading efficiency and longer sustained-release time. Ibuprofen was used as model drug. The microparticles were prepared by a novel method based on mesoporous silica and supercritical fluid (SCF) technique. The drug-loaded mesoporous silica microparticles prepared by SCF technique were analyzed by thermogravimetric analysis (TGA), N2 adsorption/desorption, scanning electron microscopy (SEM), powder X-ray diffraction (XRD) and differential scanning calorimetry (DSC). In vitro releasing study was used to evaluate the sustained-release effect of the drug-loaded microparticles. By virtue of the high diffusibility and the high dissolving capacity of the supercritical carbon dioxide (SCF-CO2), the poorly water-soluble drugs, ibuprofen, entered the pores of the mesoporous silica. The amount and the depth of ibuprofen entered the pores of the mesoporous silica by SCF technique were both larger than those by the solution immersion method. It was found that ibuprofen loaded into the mesoporous silica by SCF technique was amorphous and the largest amount of the ibuprofen loaded into the mesoporous silica by SCF technique could reach 386 mg/g (w/w, ibuprofen/SiO2), it was more than that by the solution immersion method. In vitro releasing study showed that the sustained-release effect of ibuprofen in the samples prepared by SCF technique was 50% in 15 min and 90% in 60 min. It was longer than that prepared by the solution immersion method. Present study showed that sustained-release poorly water-soluble drug mesoporous silica microparticle based on SCF technique has twofold advantages. One is the larger drug loading amount in internal pores of the mesoporous silica, the other is the longer drug releasing time. Copyright © 2013 Elsevier B.V. All rights reserved.

Carbonate pore system evaluation using the velocity-porosity-pressure relationship, digital image analysis, and differential effective medium theory

NASA Astrophysics Data System (ADS)

Lima Neto, Irineu A.; Misságia, Roseane M.; Ceia, Marco A.; Archilha, Nathaly L.; Oliveira, Lucas C.

2014-11-01

Carbonate reservoirs exhibit heterogeneous pore systems and a wide variety of grain types, which affect the rock's elastic properties and the reservoir parameter relationships. To study the Albian carbonates in the Campos Basin, a methodology is proposed to predict the amount of microporosity and the representative aspect ratio of these inclusions. The method assumes three pore-space scales in two representative inclusion scenarios: 1) a macro-mesopore median aspect ratio from the thin-section digital image analysis (DIA) and 2) a microporosity aspect ratio predicted based on the measured P-wave velocities. Through a laboratory analysis of 10 grainstone core samples of the Albian age, the P- and S-wave velocities (Vp and Vs) are evaluated at effective pressures of 0-10 MPa. The analytical theories in the proposed methodology are functions of the aspect ratios from the differential effective medium (DEM) theory, the macro-mesopore system recognized from the DIA, the amount of microporosity determined by the difference between the porosities estimated from laboratorial helium-gas and the thin-section petrographic images, and the P-wave velocities under dry effective pressure conditions. The DIA procedure is applied to estimate the local and global parameters, and the textural implications concerning ultrasonic velocities and image resolution. The macro-mesopore inclusions contribute to stiffer rocks and higher velocities, whereas the microporosity inclusions contribute to softer rocks and lower velocities. We observe a high potential for this methodology, which uses the microporosity aspect ratio inverted from Vp to predict Vs with a good agreement. The results acceptably characterize the Albian grainstones. The representative macro-mesopore aspect ratio is 0.5, and the inverted microporosity aspect ratio ranges from 0.01 to 0.07. The effective pressure induced an effect of slight porosity reduction during the triaxial tests, mainly in the microporosity inclusions, slightly changing the amount and the aspect ratio of the microporosity.

Electrochemical properties for high surface area and improved electrical conductivity of platinum-embedded porous carbon nanofibers

NASA Astrophysics Data System (ADS)

An, Geon-Hyoung; Ahn, Hyo-Jin; Hong, Woong-Ki

2015-01-01

Four different types of carbon nanofibers (CNFs) for electrical double-layer capacitors (EDLCs), porous and non-porous CNFs with and without Pt metal nanoparticles, are synthesized by an electrospinning method and their performance in electrical double-layer capacitors (EDLCs) is characterized. In particular, the Pt-embedded porous CNFs (PCNFs) exhibit a high specific surface area of 670 m2 g-1, a large mesopore volume of 55.7%, and a low electrical resistance of 1.7 × 103. The synergistic effects of the high specific surface area with a large mesopore volume, and superior electrical conductivity result in an excellent specific capacitance of 130.2 F g-1, a good high-rate performance, superior cycling durability, and high energy density of 16.9-15.4 W h kg-1 for the performance of EDLCs.

pH-Responsive Mesoporous Silica and Carbon Nanoparticles for Drug Delivery

PubMed Central

Gisbert-Garzarán, Miguel; Manzano, Miguel; Vallet-Regí, María

2017-01-01

The application of nanotechnology to medicine constitutes a major field of research nowadays. In particular, the use of mesoporous silica and carbon nanoparticles has attracted the attention of numerous researchers due to their unique properties, especially when applied to cancer treatment. Many strategies based on stimuli-responsive nanocarriers have been developed to control the drug release and avoid premature release. Here, we focus on the use of the subtle changes of pH between healthy and diseased areas along the body to trigger the release of the cargo. In this review, different approximations of pH-responsive systems are considered: those based on the use of the host-guest interactions between the nanocarriers and the drugs, those based on the hydrolysis of acid-labile bonds and those based on supramolecular structures acting as pore capping agents. PMID:28952481

Facile synthesis of hierarchical mesoporous weirds-like morphological MnO2 thin films on carbon cloth for high performance supercapacitor application.

PubMed

Shinde, Pragati A; Lokhande, Vaibhav C; Ji, Taeksoo; Lokhande, Chandrakant D

2017-07-15

The mesoporous nanostructured metal oxides have a lot of capabilities to upsurge the energy storing capacity of the supercapacitor. In present work, different nanostructured morphologies of MnO 2 have been successfully fabricated on flexible carbon cloth by simple but capable hydrothermal method at different deposition temperatures. The deposition temperature has strong influence on reaction kinetics, which subsequently alters the morphology and electrochemical performance. Among different nanostructured MnO 2 thin films, the mesoporous weirds composed thin film obtained at temperature of 453K exhibits excellent physical and electrochemical features for supercapacitor application. The weirds composed MnO 2 thin film exhibits specific surface area of 109m 2 g -1 , high specific capacitance of 595Fg -1 with areal capacitance of 4.16Fcm -2 at a scan rate of 5mVs -1 and high specific energy of 56.32Whkg -1 . In addition to this, MnO 2 weirds attain capacity retention of 87 % over 2000 CV cycles, representing better cycling stability. The enhanced electrochemical performance could be ascribed to direct growth of highly porous MnO 2 weirds on carbon cloth which provide more pathways for easy diffusion of electrolyte into the interior of electroactive material. The as-fabricated electrode with improved performance could be ascribed as a potential electrode material for energy storage devices. Copyright © 2017 Elsevier Inc. All rights reserved.

Ammonium Fluoride Mediated Synthesis of Anhydrous Metal Fluoride-Mesoporous Carbon Nanocomposites for High-Performance Lithium Ion Battery Cathodes.

PubMed

Chun, Jinyoung; Jo, Changshin; Sahgong, Sunhye; Kim, Min Gyu; Lim, Eunho; Kim, Dong Hyeon; Hwang, Jongkook; Kang, Eunae; Ryu, Keun Ah; Jung, Yoon Seok; Kim, Youngsik; Lee, Jinwoo

2016-12-28

Metal fluorides (MF x ) are one of the most attractive cathode candidates for Li ion batteries (LIBs) due to their high conversion potentials with large capacities. However, only a limited number of synthetic methods, generally involving highly toxic or inaccessible reagents, currently exist, which has made it difficult to produce well-designed nanostructures suitable for cathodes; consequently, harnessing their potential cathodic properties has been a challenge. Herein, we report a new bottom-up synthetic method utilizing ammonium fluoride (NH 4 F) for the preparation of anhydrous MF x (CuF 2 , FeF 3 , and CoF 2 )/mesoporous carbon (MSU-F-C) nanocomposites, whereby a series of metal precursor nanoparticles preconfined in mesoporous carbon were readily converted to anhydrous MF x through simple heat treatment with NH 4 F under solventless conditions. We demonstrate the versatility, lower toxicity, and efficiency of this synthetic method and, using XRD analysis, propose a mechanism for the reaction. All MF x /MSU-F-C prepared in this study exhibited superior electrochemical performances, through conversion reactions, as the cathode for LIBs. In particular, FeF 3 /MSU-F-C maintained a capacity of 650 mAh g -1 FeF3 across 50 cycles, which is ∼90% of its initial capacity. We expect that this facile synthesis method will trigger further research into the development of various nanostructured MF x for use in energy storage and other applications.

Improved Ionic Diffusion through the Mesoporous Carbon Skin on Silicon Nanoparticles Embedded in Carbon for Ultrafast Lithium Storage.

PubMed

An, Geon-Hyoung; Kim, Hyeonjin; Ahn, Hyo-Jin

2018-02-21

Because of their combined effects of outstanding mechanical stability, high electrical conductivity, and high theoretical capacity, silicon (Si) nanoparticles embedded in carbon are a promising candidate as electrode material for practical utilization in Li-ion batteries (LIBs) to replace the conventional graphite. However, because of the poor ionic diffusion of electrode materials, the low-grade ultrafast cycling performance at high current densities remains a considerable challenge. In the present study, seeking to improve the ionic diffusion, we propose a novel design of mesoporous carbon skin on the Si nanoparticles embedded in carbon by hydrothermal reaction, poly(methyl methacrylate) coating process, and carbonization. The resultant electrode offers a high specific discharge capacity with excellent cycling stability (1140 mA h g -1 at 100 mA g -1 after 100 cycles), superb high-rate performance (969 mA h g -1 at 2000 mA g -1 ), and outstanding ultrafast cycling stability (532 mA h g -1 at 2000 mA g -1 after 500 cycles). The battery performances are surpassing the previously reported results for carbon and Si composite-based electrodes on LIBs. Therefore, this novel approach provides multiple benefits in terms of the effective accommodation of large volume expansions of the Si nanoparticles, a shorter Li-ion diffusion pathway, and stable electrochemical conditions from a faster ionic diffusion during cycling.

Functionalized SBA-15 materials for bilirubin adsorption

NASA Astrophysics Data System (ADS)

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

2011-05-01

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

Chemical vapor deposition of mesoporous graphene nanoballs for supercapacitor.

PubMed

Lee, Jung-Soo; Kim, Sun-I; Yoon, Jong-Chul; Jang, Ji-Hyun

2013-07-23

A mass-producible mesoporous graphene nanoball (MGB) was fabricated via a precursor-assisted chemical vapor deposition (CVD) technique for supercapacitor application. Polystyrene balls and reduced iron created under high temperature and a hydrogen gas environment provide a solid carbon source and a catalyst for graphene growth during the precursor-assisted CVD process, respectively. Carboxylic acid and sulfonic acid functionalization of the polystyrene ball facilitates homogeneous dispersion of the hydrophobic polymer template in the metal precursor solution, thus, resulting in a MGB with a uniform number of graphene layers. The MGB is shown to have a specific surface area of 508 m(2)/g and is mesoporous with a mean mesopore diameter of 4.27 nm. Mesopores are generated by the removal of agglomerated iron domains, permeating down through the soft polystyrene spheres and providing the surface for subsequent graphene growth during the heating process in a hydrogen environment. This technique requires only drop-casting of the precursor/polystyrene solution, allowing for mass-production of multilayer MGBs. The supercapacitor fabricated by the use of the MGB as an electrode demonstrates a specific capacitance of 206 F/g and more than 96% retention of capacitance after 10,000 cycles. The outstanding characteristics of the MGB as an electrode for supercapacitors verify the strong potential for use in energy-related areas.

Reduction of Plutonium in Acidic Solutions by Mesoporous Carbons

DOE PAGES

Parsons-Moss, Tashi; Jones, Stephen; Wang, Jinxiu; ...

2015-12-19

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

Crystalline mesoporous tungsten oxide nanoplate monoliths synthesized by directed soft template method for highly sensitive NO{sub 2} gas sensor applications

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

Hoa, Nguyen Duc, E-mail: ndhoa@itims.edu.vn; Duy, Nguyen Van; Hieu, Nguyen Van, E-mail: hieu@itims.edu.vn

2013-02-15

Graphical abstract: Display Omitted Highlights: ► Mesoporous WO{sub 3} nanoplate monoliths were obtained by direct templating synthesis. ► Enable effective accession of the analytic molecules for the sensor applications. ► The WO{sub 3} sensor exhibited a high performance to NO{sub 2} gas at low temperature. -- Abstract: Controllable synthesis of nanostructured metal oxide semiconductors with nanocrystalline size, porous structure, and large specific surface area is one of the key issues for effective gas sensor applications. In this study, crystalline mesoporous tungsten oxide nanoplate-like monoliths with high specific surface areas were obtained through instant direct-templating synthesis for highly sensitive nitrogen dioxidemore » (NO{sub 2}) sensor applications. The copolymer soft template was converted into a solid carbon framework by heat treatment in an inert gas prior to calcinations in air to sustain the mesoporous structure of tungsten oxide. The multidirectional mesoporous structures of tungsten oxide with small crystalline size, large specific surface area, and superior physical characteristics enabled the rapid and effective accession of analytic gas molecules. As a result, the sensor response was enhanced and the response and recovery times were reduced, in which the mesoporous tungsten oxide based gas sensor exhibited a superior response of 21,155% to 5 ppm NO{sub 2}. In addition, the developed sensor exhibited selective detection of low NO{sub 2} concentration in ammonia and ethanol at a low temperature of approximately 150 °C.« less

A facile synthesis of mesoporous Pdsbnd ZnO nanocomposites as efficient chemical sensor

NASA Astrophysics Data System (ADS)

Ismail, Adel A.; Harraz, Farid A.; Faisal, M.; El-Toni, Ahmed Mohamed; Al-Hajry, A.; Al-Assiri, M. S.

2016-07-01

Mesoporous ZnO was synthesized through the sol-gel method in the presence of triblock co-polymer Pluronic (F-127) template as the structure directing agent. Palladium nanoparticles were photochemically reduced and deposited onto mesoporous ZnO to obtain 1 wt.% Pd/ZnO nanocomposite. Structural and morphological analysis revealed high homogeneity and monodispersity of Pd nanoclusters with small particle sizes ∼ 2-5 nm onto mesoporous ZnO. The electrochemical detection of ethanol in aqueous solutions was conducted at the newly developed Pd/ZnO modified glassy carbon electrode (GCE) by the current-potential (IV) and cyclic voltammetry (CV) techniques and compared with bare GCE or pure ZnO. The presence of Pd dopant greatly enhances the sensitivity of ZnO, and the obtained mesoporous Pd/ZnO sensor has an excellent performance for precision detection of ethanol in aqueous solution with low concentration. The sensitivity was found to be 33.08 μAcm-2 mM-1 at lower concentration zone (0.05-0.8 mM) and 2.13 μAcm-2 mM-1 at higher concentration zone (0.8-12 mM), with a limit of detection (LOD) 19.2 μM. The kinetics study of ethanol oxidation revealed a characteristic feature for a mixed surface and diffusion-controlled process. These excellent sensing characteristics make the mesoporous Pd/ZnO nanocomposite a good candidate for the production of high-performance electrochemical sensors at low ethanol concentration in aqueous solution.

Mesoporous Carbons With Self-Assembled High-Activity Surfaces (PREPRINT)

DTIC Science & Technology

2006-07-07

temperature-programmed desorption, and potentiometric titrations . Journal of Colloid and Interface Science 2001; 240: 252–258. [40] Rotkin SV, Gogotsi Y...selected carbon samples were treated with nitric acid and the total acid site density determined by base titration [32-34 Boehm 1994; Boehm 2002; 32...washed thoroughly using distilled/deionized water, and dried in the oven. For the titration , 50 mg of HNO3-treated carbon powder was added to 20 ml

A Cable-Shaped Lithium Sulfur Battery.

PubMed

Fang, Xin; Weng, Wei; Ren, Jing; Peng, Huisheng

2016-01-20

A carbon nanostructured hybrid fiber is developed by integrating mesoporous carbon and graphene oxide into aligned carbon nanotubes. This hybrid fiber is used as a 1D cathode to fabricate a new cable-shaped lithium-sulfur battery. The fiber cathode exhibits a decent specific capacity and lifespan, which makes the cable-shaped lithium-sulfur battery rank far ahead of other fiber-shaped batteries. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Preparation of ordered mesoporous and macroporous thermoplastic polyurethane surfaces for potential medical applications.

PubMed

Chennell, Philip; Feschet-Chassot, Emmanuelle; Sautou, Valérie; Mailhot-Jensen, Bénédicte

2018-05-01

Thermoplastic polyurethanes are widely used in medical devices. In order to limit some of their shortfalls, like microbial attachment, surfaces modifications can be required. In this work, a two-step replication method was used to create ordered macroporous and mesoporous thermoplastic polyurethane surfaces using anodic aluminum oxide as master template. The intermediate mould materials that were tested were polystyrene and a polyacrylate resin with inorganic filler. All obtained surfaces were characterized by scanning electron microscopy. The initial anodic aluminum oxide surfaces possessed macro or mesopores, function of anodization conditions. The intermediate mould structure correctly replicated the pattern, but the polystyrene surface structures (pillars) were less resistant than the polyacrylate resin ones. The thermoplastic polyurethane pattern possessed macropores or mesopores of about 130 nm or 46 nm diameter and of about 300 nm or 99 nm interpore distances, respectively, in accordance with the initial pattern. Thermoplastic polyurethanes pore depth was however less than initial anodic aluminum oxide pore depth, linked to an incomplete replication during intermediate mould preparation (60 to 90% depth replication). The correct replication of the original pattern confirms that this novel fabrication method is a promising route for surface patterning of thermoplastic polyurethanes that could be used for medical applications.

Hierarchically porous Li3VO4/C nanocomposite as an advanced anode material for high-performance lithium-ion capacitors

NASA Astrophysics Data System (ADS)

Xu, Xuena; Niu, Feier; Zhang, Dapeng; Chu, Chenxiao; Wang, Chunsheng; Yang, Jian; Qian, Yitai

2018-04-01

Lithium-ion capacitors, as a hybrid electrochemical energy storage device, realize high specific energy and power density within one device, thus attracting extensive attention. Here, hierarchically porous Li3VO4/C nanocomposite is prepared by a solvo-thermal reaction, followed with a post-annealing process. This composite has macropores at the center and mesopores in the wall, thus effectively promoting electrolyte penetration and structure stability upon cycling simultaneously. Compared to mesoporous Li3VO4, the enhanced rate capability and specific capacity of hierarchically porous Li3VO4/C indicate the synergistic effect of mesopores and macropores. Inspired by these results, this composite is coupled with mesoporous carbon (CMK-3) for lithium-ion capacitors, generating a specific energy density of 105 Wh kg-1 at a power density of 188 W kg-1. Even if the power density increases to 9.3 kW kg-1, the energy density still remains 62 Wh kg-1. All these results demonstrate the promising potential of hierarchically porous Li3VO4 in lithium ion capacitors.

Two-Solvent Method Synthesis of NiO/ZnO Nanoparticles Embedded in Mesoporous SBA-15: Photocatalytic Properties Study.

PubMed

Dai, Peng; Yan, Tao-Tao; Yu, Xin-Xin; Bai, Zhi-Man; Wu, Ming-Zai

2016-12-01

Different loadings of NiO/ZnO nanoparticles embedded in mesoporous silica (SBA-15) were prepared via a two-solvent method with the ordered hexagonal mesoporous structure of SBA-15 kept. X-ray diffraction, transmission electron microscope, X-ray photoelectron spectroscopy, diffusive reflective UV-vis spectroscopy, and N2 adsorption porosimetry were employed to characterize the nanocomposites. The results indicate that the ordered hexagonal mesoporous structure of SBA-15 is kept and the absorption band edges of the nanocomposites shift into the ultraviolet light regime. The photocatalytic activity of our samples for degradation of methylene orange was investigated under UV light irradiation, and the results show that the nanocomposites have higher photodegradation ability toward methylene orange than commercial pure P-25. The photocatalytic activity of the nanocomposites was found to be dependent on both the adsorption ability of the SBA-15 and the photocatalytic activity of NiO-ZnO nanoparticles encapsulated in SBA-15. In addition, there is an optimal loading of NiO-ZnO nanoparticles. Too high or low loading will lower the photodegradation ability of the nanocomposites.

Synthesis and energy applications of mesoporous titania thin films

NASA Astrophysics Data System (ADS)

Islam, Syed Z.

The optical and electronic properties of TiO2 thin films provide tremendous opportunities in several applications including photocatalysis, photovoltaics and photoconductors for energy production. Despite many attractive features of TiO2, critical challenges include the innate inability of TiO2 to absorb visible light and the fast recombination of photoexcited charge carriers. In this study, mesoporous TiO2 thin films are modified by doping using hydrogen and nitrogen, and sensitization using graphene quantum dot sensitization. For all of these modifiers, well-ordered mesoporous titania films were synthesized by surfactant templated sol-gel process. Two methods: hydrazine and plasma treatments have been developed for nitrogen and hydrogen doping in the mesoporous titania films for band gap reduction, visible light absorption and enhancement of photocatalytic activity. The hydrazine treatment in mesoporous titania thin films suggests that hydrazine induced doping is a promising approach to enable synergistic incorporation of N and Ti3+ into the lattice of surfactant-templated TiO2 films and enhanced visible light photoactivity, but that the benefits are limited by gradual mesostructure deterioration. The plasma treated nitrogen doped mesoporous titania showed about 240 times higher photoactivity compared to undoped film in hydrogen production from photoelectrochemical water splitting under visible light illumination. Plasma treated hydrogen doped mesoporous titania thin films has also been developed for enhancement of visible light absorption. Hydrogen treatment has been shown to turn titania (normally bright white) black, indicating vastly improved visible light absorption. The cause of the color change and its effectiveness for photocatalysis remain open questions. For the first time, we showed that a significant amount of hydrogen is incorporated in hydrogen plasma treated mesoporous titania films by neutron reflectometry measurements. In addition to the intrinsic modification of titania by doping, graphene quantum dot sensitization in mesoporous titania film was also investigated for visible light photocatalysis. Graphene quantum dot sensitization and nitrogen doping of ordered mesoporous titania films showed synergistic effect in water splitting due to high surface area, band gap reduction, enhanced visible light absorption, and efficient charge separation and transport. This study suggests that plasma based doping and graphene quantum dot sensitization are promising strategies to reduce band gap and enhance visible light absorption of high surface area surfactant templated mesoporous titania films, leading to superior visible-light driven photoelectrochemical hydrogen production. The results demonstrate the importance of designing and manipulating the energy band alignment in composite nanomaterials for fundamentally improving visible light absorption, charge separation and transport, and thereby photoelectrochemical properties.

Synthesis of mesoporous carbon nanoparticles with large and tunable pore sizes

NASA Astrophysics Data System (ADS)

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

2015-07-01

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

A Hierarchical MFI Zeolite with a Two-Dimensional Square Mesostructure.

PubMed

Shen, Xuefeng; Mao, Wenting; Ma, Yanhang; Xu, Dongdong; Wu, Peng; Terasaki, Osamu; Han, Lu; Che, Shunai

2018-01-15

A conceptual design and synthesis of ordered mesoporous zeolites is a challenging research subject in material science. Several seminal articles report that one-dimensional (1D) mesostructured lamellar zeolites are possibly directed by sheet-assembly of surfactants, which collapse after removal of intercalated surfactants. However, except for one example of two-dimensional (2D) hexagonal mesoporous zeolite, no other zeolites with ordered 2D or three-dimensional (3D) mesostructures have been reported. An ordered 2D mesoporous zeolite can be templated by a cylindrical assembly unit with specific interactions in the hydrophobic part. A template molecule with azobenzene in the hydrophobic tail and diquaternary ammonium in the hydrophilic head group directs hierarchical MFI zeolite with a 2D square mesostructure. The material has an elongated octahedral morphology, and quaternary, ordered, straight, square channels framed by MFI thin sheets expanded along the a-c planes and joined with 90° rotations. The structural matching between the cylindrical assembly unit and zeolite framework is crucial for mesostructure construction. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Highly ordered, accessible and nanocrystalline mesoporous TiO₂ thin films on transparent conductive substrates.

PubMed

Violi, Ianina L; Perez, M Dolores; Fuertes, M Cecilia; Soler-Illia, Galo J A A

2012-08-01

Highly porous (V(mesopore) = 25-50%) and ordered mesoporous titania thin films (MTTF) were prepared on ITO (indium tin oxide)-covered glass by a fast two-step method. The effects of substrate surface modification and thermal treatment on pore order, accessibility and crystallinity of the MTTF were systematically studied for MTTF deposited onto bare and titania-modified ITO. MTTF exposed briefly to 550 °C resulted in highly ordered films with grid-like structures, enlarged pore size, and increased accessible pore volume when prepared onto the modified ITO substrate. Mesostructure collapse and no significant change in pore volume were observed for MTTF deposited on bare ITO substrates. Highly crystalline anatase was obtained for MTTF prepared on the modified-ITO treated at high temperatures, establishing the relationship between grid-like structures and titania crystallization. Photocatalytic activity was maximized for samples with increased crystallization and high accessible pore volume. In this manner, a simple way of designing materials with optimized characteristics for optoelectronic applications was achieved through the modification of the ITO surface and a controlled thermal treatment.

Preparation, microstructure and hydrogen sorption properties of nanoporous carbon aerogels under ambient drying.

PubMed

Tian, H Y; Buckley, C E; Mulè, S; Paskevicius, M; Dhal, B B

2008-11-26

Organic aerogels are prepared by the sol-gel method from polymerization of resorcinol with furfural. These aerogels are further carbonized in nitrogen in order to obtain their corresponding carbon aerogels (CA); a sample which was carbonized at 900 °C was also activated in a carbon dioxide atmosphere at 900 °C. The chemical reaction mechanism and optimum synthesis conditions are investigated by means of Fourier transform infrared spectroscopy and thermoanalyses (thermogravimetric/differential thermal analyses) with a focus on the sol-gel process. The carbon aerogels were investigated with respect to their microstructures, using small angle x-ray scattering (SAXS), transmission electron microscopy (TEM) and nitrogen adsorption measurements at 77 K. SAXS studies showed that micropores with a radius of gyration of <0.35 ± 0.07 to 0.55 ± 0.05 nm were present, and TEM measurements and nitrogen adsorption showed that larger mesopores were also present. Hydrogen storage properties of the CA were also investigated. An activated sample with a Brunauer-Emmett-Teller surface area of 1539 ± 20 m(2) g(-1) displayed a reasonably high hydrogen uptake at 77 K with a maximum hydrogen sorption of 3.6 wt% at 2.5 MPa. These results suggest that CA are promising candidate hydrogen storage materials.

Preparation, microstructure and hydrogen sorption properties of nanoporous carbon aerogels under ambient drying

NASA Astrophysics Data System (ADS)

Tian, H. Y.; Buckley, C. E.; Mulè, S.; Paskevicius, M.; Dhal, B. B.

2008-11-01

Organic aerogels are prepared by the sol-gel method from polymerization of resorcinol with furfural. These aerogels are further carbonized in nitrogen in order to obtain their corresponding carbon aerogels (CA); a sample which was carbonized at 900 °C was also activated in a carbon dioxide atmosphere at 900 °C. The chemical reaction mechanism and optimum synthesis conditions are investigated by means of Fourier transform infrared spectroscopy and thermoanalyses (thermogravimetric/differential thermal analyses) with a focus on the sol-gel process. The carbon aerogels were investigated with respect to their microstructures, using small angle x-ray scattering (SAXS), transmission electron microscopy (TEM) and nitrogen adsorption measurements at 77 K. SAXS studies showed that micropores with a radius of gyration of <0.35 ± 0.07 to 0.55 ± 0.05 nm were present, and TEM measurements and nitrogen adsorption showed that larger mesopores were also present. Hydrogen storage properties of the CA were also investigated. An activated sample with a Brunauer-Emmett-Teller surface area of 1539 ± 20 m2 g-1 displayed a reasonably high hydrogen uptake at 77 K with a maximum hydrogen sorption of 3.6 wt% at 2.5 MPa. These results suggest that CA are promising candidate hydrogen storage materials.

Growth of nanostructures with controlled diameter

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

Pfefferle, Lisa; Haller, Gary; Ciuparu, Dragos

2009-02-03

Transition metal-substituted MCM-41 framework structures with a high degree of structural order and a narrow pore diameter distribution were reproducibly synthesized by a hydrothermal method using a surfactant and an anti-foaming agent. The pore size and the mesoporous volume depend linearly on the surfactant chain length. The transition metals, such as cobalt, are incorporated substitutionally and highly dispersed in the silica framework. Single wall carbon nanotubes with a narrow diameter distribution that correlates with the pore diameter of the catalytic framework structure were prepared by a Boudouard reaction. Nanostructures with a specified diameter or cross-sectional area can therefore be predictablymore » prepared by selecting a suitable pore size of the framework structure.« less

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

PubMed Central

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

2015-01-01

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

Freezing and melting of water in a single cylindrical pore: The pore-size dependence of freezing and melting behavior

NASA Astrophysics Data System (ADS)

Morishige, Kunimitsu; Kawano, Keiji

1999-03-01

In order to clarify the origin of the hysteresis between freezing and melting of pore water, we performed x-ray diffraction measurements of water confined inside the cylindrical pores of seven kinds of siliceous MCM-41 (a member of ordered mesoporous materials denoted by Mobil Oil researchers) with different pore radii (1.2-2.9 nm) and the interconnected pores of Vycor glass as a function of temperature. The hysteresis effect depends markedly on the size of the cylindrical pores: the hysteresis is negligibly small in smaller pores and becomes remarkable in larger pores. This strongly suggests that the hysteresis is arisen from size-dependent supercooling of water confined to the mesopores. For the water confined to the mesopores with pore radius of 1.2 nm, a continuous transition between a liquid and a solid precedes the first-order freezing transition of the pore water which would occur by the same mechanism as in bulk water.

Encapsulation of mangiferin in ordered mesoporous silica type SBA-15: synthesis and characterization

NASA Astrophysics Data System (ADS)

Pontes Silva, Cássia Roberta; da Rocha Ferreira, Fabricia; Dresch Webler, Geovana; Osimar Sousa da Silva, Antônio; Caxico de Abreu, Fabiane; Fonseca, Eduardo J. S.

2017-06-01

SBA-15 ordered mesoporous silica were synthesized using the method reported by Zhao et al (1998 J. Am. Chem. Soc. 120 6024-36). The goal of this work is to study the encapsulation of mangiferin (MGN) into porous SBA-15. SBA-MGN composites were obtained from a mixture of SBA-15 and MGN. The structures of these materials were analyzed using different characterization techniques: differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), N2 adsorption-desorption measurement, transmission electron microscopy (TEM), absorbance spectra and electrochemical assay. The isotherms of the adsorption/desorption for SBA-15 and SBA-MGN are type IV, showing that the ordered mesoporous structure of SBA-15 was maintained even after the incorporation of MGN. The decrease in the value of the specific surface area and the reduction in pore volume confirmed the incorporation of MGN at the surface and in the pores of SBA-15. The incorporation of MGN in SBA-15 aims to increase the solubility of mangiferin.

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

PubMed

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

2010-07-15

Two types of activated carbons from tyre char (with or without sulphuric acid treatment) were produced via carbon dioxide activation with BET surface areas in the range 59-1118 m(2)/g. Other characterisation tests include micropore and mesopore surface areas and volumes, pH, and elemental compositions, particularly heteroatoms such as nitrogen and sulphur. They were correlated to the adsorption capacity which were in the range of 0.45-0.71 mmol/g (untreated) and 0.62-0.84 mmol/g (acid-treated) for Acid Blue 25. In the case of larger-sized molecules like Acid Yellow 117, capacities were in the range of 0.23-0.42 mmol/g (untreated) and 0.29-0.40 mmol/g (acid-treated). Some tyre carbons exhibit a more superior performance than a microporous, commercial activated carbon (Calgon F400). By modelling the dye adsorption equilibrium data, the Redlich-Peterson isotherm is adopted as it has the lowest SSE. Based on the surface coverage analysis, a novel molecular orientation modelling of adsorbed dyes has been proposed and correlated with surface area and surface charge. For the acid dyes used in this study, molecules were likely to be adsorbed by the mesopore areas. Copyright 2010 Elsevier Inc. All rights reserved.

Controlled release of alendronate from nitrogen-doped mesoporous carbon

DOE PAGES

Saha, Dipendu; Spurri, Amanda; Chen, Jihua; ...

2016-04-13

With this study, we have synthesized a nitrogen doped mesoporous carbon with the BET surface area of 1066 m 2/g, total pore volume 0.6 cm 3/g and nitrogen content of 0.5%. Total alendronate adsorption in this carbon was ~5%. The release experiments were designed in four different media with sequential pH values of 1.2, 4.5, 6.8 and 7.4 for 3, 1, 3 and 5 h, respectively and at 37 °C to imitate the physiological conditions of stomach, duodenum, small intestine and colon, respectively. Release of the drug demonstrated a controlled fashion; only 20% of the drug was released in themore » media with pH = 1.2, whereas 64% of the drug was released in pH = 7.4. This is in contrary to pure alendronate that was completely dissolved within 30 min in the first release media (pH = 1.2) only. The relatively larger uptake of alendronate in this carbon and its sustained fashion of release can be attributed to the hydrogen bonding between the drug and the nitrogen functionalities on carbon surface. Based on this result, it can be inferred that this formulation may lower the side effects of oral delivery of alendronate.« less

A nitrogen-doped 3D hierarchical carbon/sulfur composite for advanced lithium sulfur batteries

NASA Astrophysics Data System (ADS)

Liu, Xiaoyan; Huang, Wenlong; Wang, Dongdong; Tian, Jianhua; Shan, Zhongqiang

2017-07-01

Hybrid nanostructures containing one-dimensional (1D) carbon nanotubes (CNTs) and three-dimensional (3D) mesoporous carbon sphere have many promising applications due to their unique physical chemical properties. In this study, a novel 3D hierarchical carbon material (MCCNT) composed of mesoporous carbon sphere core and nitrogen rich CNTs shell is successfully prepared via an aerosol spray and subsequent chemical vapor deposition (CVD) processes. Owning to its well defined porous structure and favorable conductive framework, MCCNT is used as a potential sulfur host in lithium sulfur batteries through a classic melt-diffusion method. When cycled at a current density of 0.2 C (1 C = 1675 mA h g-1), it delivers an initial capacity as high as 1438.7 mAh g-1. Even if the current density increase to 1 C, the specific capacity still remain up to 534.6 mAh g-1 after 300 cycles. The enhanced electrochemical performance can be attributed to the hybrid structure of MCCNT, in which, the porous core works as a host to confine sulfur and accommodate volume expansion and the external CNTs provide excellent electron and ion conductive frame work. Furthermore, the in-situ doped nitrogen on the surface of CNTs enables effective trapping of lithium polysulfides, leading to a much-improved cycling performance.

Photoluminescence of carbon dots from mesoporous silica

NASA Astrophysics Data System (ADS)

Nelson, D. K.; Razbirin, B. S.; Starukhin, A. N.; Eurov, D. A.; Kurdyukov, D. A.; Stovpiaga, E. Yu; Golubev, V. G.

2016-09-01

Photophysical properties of carbon dots were investigated under various excitation conditions and over a wide temperature region - from room to liquid helium temperatures. The carbon dots (CDs) were synthesized using mesoporous silica particles as a reactor and (3-aminopropyl)triethoxysilane (APTES) as a precursor. The photoluminescence spectra of CDs exhibit a strong dependence on the excitation wavelength and demonstrate a significant inhomogeneous broadening. Lowering sample temperature reveals the doublet structure of the spectra, which is associated with the vibronic structure of radiative transitions. The vibration energy ∼1200 cm-1 is close to the energy of Csbnd O stretching vibration. Long-lived phosphorescence of carbon dots with its decay time ∼0.2 s at T = 80 K was observed. The fluorescence and phosphorescence spectra are shown to be spectrally separated. The long-lived component of the emission was ascribed to optically forbidden triplet-singlet transitions. The value of the singlet-triplet splitting was found to be about 0.3 eV. Photo-induced polarization of the luminescence of carbon dots was revealed. The degree of the linear polarization is dependent on the wavelengths of both excitation and emitted light. The effect indicates a hidden anisotropy of optical dipole transitions in the dots and demonstrates the loss of the dipole orientation during the electron energy relaxation.

Enhancing substrate utilization and power production of a microbial fuel cell with nitrogen-doped carbon aerogel as cathode catalyst.

PubMed

Tardy, Gábor Márk; Lóránt, Bálint; Lóka, Máté; Nagy, Balázs; László, Krisztina

2017-07-01

Catalytic efficiency of a nitrogen-doped, mesoporous carbon aerogel cathode catalyst was investigated in a two-chambered microbial fuel cell (MFC) applying graphite felt as base material for cathode and anode, utilizing peptone as carbon source. This mesoporous carbon aerogel containing catalyst layer on the cathode increased the maximum power density normalized to the anode volume to 2.7 times higher compared to the maximum power density obtained applying graphite felt cathode without the catalyst layer. At high (2 and 3) cathode/anode volume ratios, maximum power density exceeded 40 W m -3 . At the same time, current density and specific substrate utilization rate increased by 58% resulting in 31.9 A m -3 and 18.8 g COD m -3  h -1 , respectively (normalized to anode volume). Besides the increase of the power and the rate of biodegradation, the investigated catalyst decreased the internal resistance from the range of 450-600 to 350-370 Ω. Although Pt/C catalyst proved to be more efficient, a considerable decrease in the material costs might be achieved by substituting it with nitrogen-doped carbon aerogel in MFCs. Such cathode still displays enhanced catalytic effect.