Nitrogen-containing Mesoporous Carbon Research Articles

Effects of surface functional groups of the N-containing carbon support on the catalytic properties of supported palladium

Nitrogen-containing mesoporous carbons (SNMC) were shaped by the drop ball method. A SNMC and a commercial coconut shell carbon (CSC) were oxidized by nitric acid to obtain the OSNMC and OCSC supports. Then, the Pd/OSNMC, Pd/SNMC, Pd/OCSC and Pd/CSC catalysts (5%wt) were prepared to study the effects of carboxyl group on the hydrogenation of C=C double bond. The results showed that both the doped N and surface O-containing functional groups increased the dispersion and surface electron density of supported Pd, leading to the increased heats for the adsorption of hexene and H 2 and thus the increased intrinsic activity for the hydrogenation of hexene on Pd. The pre-adsorption of propionic acid (PA) significantly inhibited the adsorption of hexene and H 2 and decreased the conversion of hexene on Pd. However, the surface O-containing functional groups inhibited the adsorption of carboxyl groups and offset the inhibition effect of carboxyl groups on the hydrogenation of hexene on Pd, while the doped N atoms played the opposite role. Thus, it is expected that the surface O-containing functional groups are beneficial to the hydrogenation of unsaturated fatty acids on Pd/C catalysts. The doped N and surface O-containing functional groups in carbon supports were electron donators that increased the electron charges of supported Pd on which the adsorption of hexene was enhanced and led to the increase in intrinsic activity for the hydrogenation of hexene. The strong adsorption of propionic acid (PA) inhibited the adsorption of hexene and lowered the conversion of hexene on Pd/C, which was offset by the surface O-containing functional groups. • Doped N in C supports enhanced dispersion of Pd and donated electron charges to Pd. • Surface O groups also enhanced dispersion of Pd and donated electron charges to Pd. • Electron enriched Pd favored adsorption of hexene and thus its hydrogenation. • Carboxyl groups strongly inhibited adsorption of hexene and thus its hydrogenation. • Surface O groups offset inhibition effect of -COOH on adsorption of hexene on Pd.

Branched Poly(l-lysine)-Derived Nitrogen-Containing Porous Carbon Flake as the Metal-Free Electrocatalyst toward Efficient Oxygen Reduction Reaction

Amino acids are recently being regarded as highly attractive candidates to fabricate thoroughly metal-free and rich nitrogen-containing mesoporous carbons. Nevertheless, the carbonization yield of ...

Monodisperse Ultrahigh Nitrogen-Containing Mesoporous Carbon Nanospheres from Melamine-Formaldehyde Resin.

An aqueous emulsion polymerization self-assembly approach is demonstrated for the first time to synthesize ultrahigh nitrogen containing mesoporous polymer nanospheres, using melamine-formaldehyde resin oligomers as precursors. In the synthesis, change from alkaline to acidic conditions is critical for the formation of monodisperse mesostructured polymer nanospheres. Owing to unique structure of triazine stabilized in the covalent polymeric networks during the pyrolysis process, the derived mesoporous carbon nanospheres possess an ultrahigh nitrogen content (up to 15.6 wt%) even after pyrolysis at 800°C, which is the highest nitrogen content among mesoporous carbon nanospheres. Furthermore, these monodisperse mesoporous carbon nanospheres possess a high surface area (≈883 m2 g-1 ) and large pore size (≈8.1nm). As an anode for sodium-ion batteries, the ultrahigh nitrogen-containing mesoporous carbon nanospheres exhibit superior rate capability (117 mAh g-1 at a high current density of 3 A g-1 ) and high reversible capacity (373 mAh g-1 at 0.06 A g-1 ), indicating a promising material for energy storage.

Post-KOH activation of nitrogen-containing porous carbon with ordering mesostructure synthesized through a self-assembly

The effects of KOH activation on pore textural characteristics of nitrogen-containing mesoporous carbon have been investigated. Adjustment KOH/carbon weight ratio and activation temperature can lead to remarkable increases in BET surface area and total volume up to 1652 m2/g and 0.92 cm3/g, under the existence of periodicity of mesopore. The large increase in micro- and mesopore volume with simultaneous maintenance of mesostructure mainly is attributed to the etching of mesopore wall and shrinkage of carbon framework. It is shown that the development of porosity as well as the nitrogen basic sites would induce the excellent performance for CO2 adsorption and separation.

Synthesis and characterization of nitrogen-containing hydrothermal carbon with ordered mesostructure

One-pot hydrothermal synthetic approach for preparing nitrogen-containing mesoporous carbons with high surface area and rich nitrogen content through organic-organic self-assembly of ampliphilic triblock copolymer (Pluronic F127), phenolic resins and ethylenediamine as nitrogen source has been achieved. Ethylenediamine molecules participate in cross-linking of resorcinol and aldehyde, whereas the formed resin molecules bridge with Pluronic F127 via hydrogen bonding during hydrothermal process, leading to the formation of nitrogen-containing carbons with ordered mesostructure during pyrolysis at 800 °C. The obtained nitrogen-containing carbon had a large surface area and pore volume, nitrogen incorporated into carbon frameworks was capable for enhancing the CO2 adsorption capacity.

Knoevenagel condensation reactions catalyzed by nitrogen-containing mesoporous carbon materials under mild reaction conditions

A series of nitrogen-containing ordered mesoporous carbon (NOMC) materials have been prepared by a convenient soft-templating method. The physicochemical properties of the NOMC samples were characterized by N2 adsorption and desorption, small-angle XRD, FT-IR, XPS, and TEM. As solid base catalysts, NOMCs exhibited remarkable catalytic activities for Knoevenagel condensation reactions under mild reaction conditions, depending on their synthetic calcination temperature. Among them, NOMC-500 showed the highest catalytic activity. For Knoevenagel condensation of benzaldehyde and malononitrile, the conversion of aldehyde was higher than 85% under 50 °C. Moreover, the catalysts had good catalytic applicability for wide substrates. The catalytic activity obtained on NOMC catalyst is compared with other nitrogen-containing carbon-based materials. Nitrogen-containing ordered mesoporous carbon materials, prepared by a soft-templating method under aqueous solution and as solid base catalysts, demonstrated high catalytic activity in Knoevenagel condensation reactions under mild reaction conditions.

Hierarchical porous carbon templated with silica spheres of a diameter of 14\xa0nm from pure chitosan or a chitosan/ZnCl2 solution

Nitrogen-containing mesoporous carbons with the use of colloidal silica spheres of (14 nm) and chitosan as a carbon precursor were obtained. A removal of such small template particles from carbonized silica–chitosan composite is difficult and HF with a minimum concentration of 15 wt% should be used. By varying the silica-to-chitosan ratio, the porous characteristic of products is controlled. The modification by ZnCl2 with a molar Zn-to-C (in chitosan mass) ratio of ‘6’ results in the development of microporosity; however it is accompanied by a significant reduction of mesopore volume (Vmes). The addition of ZnCl2 in a ratio of ‘5.25’ and pH adjustment to 5.8 increase the volumes of micropores, small mesopores, BET surface area to 1975 m2/g, and preserve Vmes of 4.15 cm3/g. The novelty of the presented strategy is the creation of microporosity in the hard-templated materials by incorporating ZnCl2 into the mixture of Ludox HS-40 template and chitosan precursor, as well as the investigation on how the pH of synthesis influences the final porosity. The pH of a silica–chitosan–zinc solution, equal to 3.9, provides some coordination of Zn2+ by –OH and –NH2 groups, whereas pH adjustment to 5.8 results in the precipitation of a new template—Zn(OH)2.

N-doped mesoporous carbons supported palladium catalysts prepared from chitosan/silica/palladium gel beads

In this study, a heterogeneous catalyst including palladium nanoparticles supported on nitrogen-doped mesoporous carbon (Pd@N-C) is synthesized from palladium salts as palladium precursor, colloidal silica as template, and chitosan as carbon source. N2 sorption isotherm results show that the prepared Pd@N-C had a high BET surface area (640m2g−1) with large porosity. The prepared Pd@N-C is high nitrogen-rich as characterized with element analysis. X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HR-TEM), and Raman spectroscopy characterization of the catalyst shows that the palladium species with different chemical states are well dispersed on the nitrogen-containing mesoporous carbon. The Pd@N-C is high active and shows excellent stability as applied in Heck coupling reactions. This work supplies a successful method to prepare Pd heterogeneous catalysts with high performance from bulk biopolymer/Pd to high porous nitrogen-doped carbon supported palladium catalytic materials.

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

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

ChemInform Abstract: Mesoporous Carbons: Recent Advances in Synthesis and Typical Applications

AbstractReview: 509 refs.

Nitrogen-containing mesoporous carbons with high capacitive properties derived from a gelatin biomolecule

Nitrogen-rich mesoporous carbons were synthesized using an inexpensive and readily available gelatin biopolymer as a carbon/nitrogen precursor and colloidal silica as a hard template. The resulting materials exhibited large pore volumes of up to 4.38cm3/g, bimodal porosity (pores centered at approximately 3 and 24–28nm) and contained high levels of bulk and surface nitrogen (up to 10wt% and 5.8at.%, respectively).The electrochemical properties of the carbons were evaluated in 6M KOH and 1M H2SO4 aqueous solutions via cyclic voltammetry, galvanostatic charge/discharge cycling and electrochemical impedance spectroscopy. The samples exhibited high capacitances of up to 230 and 335F/g in alkaline and acidic solutions, respectively. The capacitance retention in the acidic solution at a high potential sweep rate (100mV/s) was lower (75–80%) than that in the alkaline medium (∼94%), suggesting that pseudocapacitance contributes less effectively in quick charge/discharge operations.The influence of the chemistry of gelatin on its compatibility with colloidal silica is discussed. It is shown that if the values of the isoelectric point of the gelatin and the pH of the colloidal silica solution are similar, then excessive self-association and precipitation may occur, thereby decreasing the porosity of the resulting carbons.

Size-controlled nitrogen-containing mesoporous carbon nanospheres by one-step aqueous self-assembly strategy

Nitrogen-containing mesoporous carbon nanospheres have been prepared through an aqueous self-assembly process with F127 as a template and morphological control agent, and 3-aminophenol as carbon and nitrogen sources.

Gelatin-pyrolyzed mesoporous carbon as a high-performance sodium-storage material

Nitrogen-containing mesoporous carbons obtained by co-pyrolyzing gelatin and magnesium citrate at different temperatures show high reversible sodium storage capacity (up to 360 mA h g−1) and excellent cycling stability.

Nitrogen-containing mesoporous carbon cathode for lithium-oxygen batteries: The influence of Nitrogen on oxygen reduction reaction

The direct effect of nitrogen content and various nitrogen species on oxygen reduction reaction (ORR) activities in non-aqueous lithium-oxygen (Li-O2) batteries are systematically investigated. Mesoporous carbon (MC) with various nitrogen species is prepared through heat treatment of N-containing precursor under different temperature. The effect of the heat treatment temperature on the performance of carbon materials in Li-O2 battery is investigated. The bonding state of nitrogen atoms is found to have a significant effect on the ORR activity. The ORR activity in Li-O2 battery is proved to be dependent on the quaternary N content while the total N content in the carbon material does not play a crucial role in the ORR process.

One-pot synthesis of highly ordered nitrogen-containing mesoporous carbon with resorcinol–urea–formaldehyde resin for CO2 capture

Nitrogen-containing ordered mesoporous carbon has been prepared by a soft-templating strategy, without using intricate prepolymerization and hydrothermal solidification steps. This strategy involves the use of hexamethylenetetramine, slow releasing source of formaldehyde for the self-assembly of resorcinol–urea–formaldehyde resin, to mediate the formation of nitrogen enriched carbon organic precursor, whereas ampliphilic triblock copolymer (Pluronic F127) was used as a template. Small angle X-ray diffraction, transmission electron microcopy, nitrogen sorption demonstrated that the obtained mesoporous carbon possessed a body-centered cubic Im3‾m structure with a high surface area. X-ray photoelectron spectroscopy revealed that the incorporated nitrogen was present in the form of pyridine, pyrrolyic/pyridine, quaternary and oxidized nitrogen. The presence of nitrogen groups in the resulting material significantly improved the CO2 adsorption capacity for mesoporous carbon (3.3mmolg−1 at 0°C, 2.6mmolg−1 at 25°C) and activated mesocarbon (4.9mmolg−1 at 0°C, 3.1mmolg−1 at 25°C) at 0.95bar. This feature substantiates N-doped mesoporous carbon as a promising high-performance CO2 capture sorbent.

Enhanced Supercapacitor Performance of N‐Doped Mesoporous Carbons Prepared from a Gelatin Biomolecule

Nitrogen-containing mesoporous carbon electrodes with tunable pore diameters for supercapacitor applications are synthesized by the nanocasting technique using a naturally abundant gelatin polymer as the single precursor for nitrogen and carbon.

Preparation of nitrogen-containing mesoporous carbons and their application in supercapacitors

Nitrogen-containing mesoporous carbons (NMCs) were prepared from quinoline-polymerized pitch using mesoporous silica as a template. The effects of the ratio of quinoline-polymerized pitch/silica template and carbonization temperature on the capacitive performance of NMCs were extensively studied. The NMC synthesized at a pitch–silica template ratio of 1.5 and carbonized at 750 °C has a high surface area of 1000 m2 g−1 and a high nitrogen content of 5.43%. The unique pore structure and nitrogen functionalities enable the carbon to exhibit a high capacitance of up to 290 F g−1 in 1 mol L−1 H2SO4 aqueous electrolytes.

Novel nitrogen-containing mesoporous carbons prepared from chitosan

In this study, synthesis of novel nitrogen-containing mesoporous carbons with the use of both colloidal silica as a template and chitosan as a new promising carbon precursor was performed. The prepared materials were characterized by adsorption of nitrogen, high-resolution transmission electron microscopy (HR-TEM), scanning electron microscopy, Raman spectroscopy, and elemental analysis. The use of the silica template makes it possible to achieve products of the pore volume as high as 4.31 cm3 g−1, with only insignificant contribution of microporosity. The present method enables the synthesis of nitrogen-containing carbons in a simple manner, using an inexpensive and readily available biopolymer.

Nitrogen-containing mesoporous carbons prepared from melamine formaldehyde resins with CaCl 2 as a template

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

Preparation, characterization, and catalytic activity of H5PMo10V2O40 immobilized on nitrogen-containing mesoporous carbon (PMo10V2/N-MC) for selective conversion of methanol to dimethoxymethane

Nitrogen-containing mesoporous carbon (N-MC) was synthesized by a templating method using SBA-15 and polypyrrole as a templating agent and a carbon precursor, respectively. The N-MC was then modified to have a positive charge, and thus, to provide a site for the immobilization of [PMo10V2O40]5−. By taking advantage of the overall negative charge of [PMo10V2O40]5−, H5PMo10V2O40 (PMo10V2) catalyst was chemically immobilized on the N-MC support as a charge-matching component. Characterization results showed that nitrogen in the N-MC played an important role in forming a nitrogen-derived functional group (amine group), and PMo10V2 catalyst was finely and chemically immobilized on the nitrogen-derived functional group of N-MC support. In the vapor-phase selective conversion of methanol, the PMo10V2/N-MC catalyst showed a higher conversion of methanol than the bulk PMo10V2 catalyst. Furthermore, the PMo10V2/N-MC catalyst showed a higher selectivity for dimethoxymethane (a product formed by bifunctional oxidation-acid-acid catalysis) and a higher selectivity for methylformate (a product formed by bifunctional oxidation-acid-oxidation catalysis) than the PMo10V2 catalyst. Reaction pathway for selective conversion of methanol to dimethoxymethane over PMo10V2/N-MC catalyst could be controlled by changing the methanol feed rate.