Ordered Mesoporous Carbon Materials Research Articles

General strategy for embedding metallic element, multi-metal or metal alloy nanoparticles into ordered mesoporous carbons via alcohol-soluble humins

Supported metal nanoparticles (NPs) have many potential applications in environmental, energy and catalysis fields. Herein, a general strategy for embedding metallic element, multi-metal or metal alloy nanoparticles into ordered mesoporous carbons (OMCs) with one pot reaction is described that uses alcohol-soluble humins as carbon precursors, metal ions as metal NP precursors and nonionic surfactant (F127) in ethanol with evaporation induced self-assembly (EISA) soft-template method. The synthesis method for NP@OMC materials is applicable to single metals (Fe, Co, Ni, Zn, Ru, Mg, Ca, and Zr) or multiple metals and allows formation of mono-metal nanoparticle or alloy nanoparticle-embedded OMC materials with dense loadings of up to ca. 20 wt%. As proof-of-concept, the catalytic performance of FexNiy@OMC for glucose hydrogenation at controlled stoichiometric ratios (x: 0, 1, 3; y: 3, 1, 0) were shown to give sorbitol yields of 99.6% at 160 °C in 3 h reaction time. The FexNiy@OMC materials outperformed reported Ru catalysts for glucose hydrogenation and their structure and dispersion in the OMC inhibited Ni agglomeration and leaching. The proposed general strategy, which uses alcohol-soluble humins carbon precursors, is broadly applicable to single or multiple metals and allows simple control of metal or metallic element NP composition, metal NP loading and NP dispersion in metal NP-embedded ordered mesoporous carbon materials.

Cobalt cross-linked ordered mesoporous carbon as peroxymonosulfate activator for sulfamethoxazole degradation

Ordered mesoporous carbons (OMCs) functionalized with catalytically-active metals have many potential applications in sulfate radical-based advanced oxidation processes for degrading antibiotics. Cobalt cross-linked ordered mesoporous carbon materials (OMC-Co-Tx) were synthesized through evaporation-induced self-assembly, calcinated at (600 to 800) oC. The OMC-Co-Tx materials were then employed as peroxymonosulfate (PMS) activators for removal of sulfamethoxazole (SMX) from aqueous solutions. OMC-Co-T800 prepared by calcination at 800 °C had a large specific surface area (449 m2/g), uniform pore structure (∼4.5 nm) and showed the best performance for activation of PMS. With a dosage of 0.1 g/L OMC-Co-T800 and 0.4 g/L PMS, the functionalized OMC material allowed SMX (10 mg/L) removal of up to 99% in 30 min. The increase of calcination temperature promoted the reduction of cobalt in OMC materials and increased the defects in their structure, resulting in better catalyst behavior. Quenching experiments and electron paramagnetic resonance analyses showed that reactive species of sulfamethoxazole degradation involved in the OMC-T800/PMS system were SO4•−, OH, O2•− and 1O2. HPLC-MS analyses of degradation intermediates formed in the OMC-Co-T800/PMS system allowed elucidation of four transformation pathways for SMX degradation.

Simplified Steps to Synthesize Ordered Mesoporous Carbon Materials with High Carbon Dioxide Capturing Performance

Simplified Steps to Synthesize Ordered Mesoporous Carbon Materials with High Carbon Dioxide Capturing Performance

Cobalt-, iron- and nitrogen-containing ordered mesoporous carbon-based catalysts for anion-exchange membrane fuel cell cathode

Cobalt-, iron- and nitrogen-doped ordered mesoporous carbon (OMC)-based electrocatalysts are prepared, characterized, and used as cathode catalysts in anion-exchange membrane fuel cell (AEMFC). The OMC material is synthesized using a green and simple route via soft-template method and without the usage of harsh chemicals. To study the effect of porous structure of carbon support on the electrocatalytic properties, the OMC material is also mixed either with carbide-derived carbon (CDC) or carbon nanotubes (CNTs). Doping of carbon nanomaterials is done via high-temperature pyrolysis in the presence of cobalt and iron acetate as well as 1,10-phenanthroline. The physico-chemical characterization shows that the preparation of OMC and subsequent doping of nanocarbons has been successful, and the catalysts contain single-atom M-Nx centres. The initial assessment employing the rotating disc electrode method indicates that all three doped catalyst materials exhibit very high electrocatalytic activity toward the oxygen reduction reaction (ORR) in alkaline media and good stability after 10,000 potential cycles. In AEMFC testing with AEMION+ anion exchange membrane, the prepared cathode catalysts show good performance with CoFe-N-OMC/CNT obtaining the highest peak power density of 336 mW cm–2. Slightly lower AEMFC performance observed for CoFe-N-OMC and CoFe-N-OMC/CDC cathodes indicates that it is influenced by the catalyst's porous structure. It can be concluded that the OMC-based materials are promising cathode catalysts for AEMFC application.

Synthesis of self-renewing Fe(0)-dispersed ordered mesoporous carbon for electrocatalytic reduction of nitrates to nitrogen.

In electrocatalytic reduction of nitrates to nitrogen, key issues are electrode activity, sustainable materials, preparation methods and cost. Herein, lignin, Fe3+ ion, and non-ionic surfactant were combined with evaporation-induced self-assembly (EISA) to prepare zero-valent Fe-dispersed ordered mesoporous carbon (OMC) electrode materials denoted as Fe#OMC. The method developed for preparing Fe-coordinated OMC material avoids the use of toxic phenols, aldehyde reagents and metal doping compounds. When synthesized Fe#OMC samples were applied as electrode materials for the electrocatalytic reduction of nitrate in aqueous solutions, maximum nitrate nitrogen removal was as high as 5373 mg N·g-1 Fe from aqueous solutions containing 400 mg·L-1 NO3--N, while nitrogen selectivity was close to 100%, exceeding catalytic performance of comparable materials. Active hydrogen produced by electrolysis of water during the reaction re-reduced Fe ions formed in the OMC material and stabilized Fe#OMC electrode performance and recycle. The Fe#OMC electrode is self-renewing with respect to its Fe zero-valent state, is simple to prepare from sustainable materials and is effective for electrocatalytic reduction of nitrate or nitrogen-containing compounds in water.

Molybdenum Sulfide (MoS2)/Ordered Mesoporous Carbon (OMC) Tubular Mesochannel Photocatalyst for Enhanced Photocatalytic Oxidation for Removal of Volatile Organic Compounds (VOCs).

Air pollutants cause severe problems in urban areas, specifically in terms of toxicological impacts on human health. Therefore, it is urgent to develop an effective, safe, and inexpensive technique to remove these air pollutants. In this study, the MoS2/OMC heterojunction photocatalyst was successfully synthesized by a hydrothermal process and used for improving photocatalytic oxidation performance for removing VOCs. Formaldehyde was used as a model VOC in the gas phase and was removed at room temperature under visible light irradiation. For my research, the microstructure and morphology of the photocatalyst were deeply characterized, and the results indicated that MoS2 were successfully coupled into OMC materials to prepare MoS2/OMC heterojunction photocatalysts. The trend of photocatalytic efficiency for formaldehyde decomposition was MoS2/OMC > MoS2 > OMC. Besides, the MoS2/OMC heterojunction photocatalyst showed an excellent regeneration performance after several recycles, indicating the potential of MoS2/OMC composite as a promising photocatalyst for VOC removal. These results indicated that the photocatalytic reactor containing MoS2/OMC photocatalysts was highly active and stable.

Noncovalent Immobilization of Pentamethylcyclopentadienyl Iridium Complexes on Ordered Mesoporous Carbon for Electrocatalytic Water Oxidation

The attachment of molecular catalysts to conductive supports for the preparation of solid‐state anodes is important for the development of devices for electrocatalytic water oxidation. The preparation and characterization of three molecular cyclopentadienyl iridium(III) complexes, Cp*Ir(1‐pyrenyl(2‐pyridyl)ethanolate‐κO,κN)Cl (1) (Cp* = pentamethylcyclopentadienyl), Cp*Ir(diphenyl(2‐pyridyl)methanolate‐κO,κN)Cl (2), and [Cp*Ir(4‐(1‐pyrenyl)‐2,2′‐bipyridine)Cl]Cl (3), as precursors for electrochemical water oxidation catalysts, are reported. These complexes contain aromatic groups that can be attached via noncovalent π‐stacking to ordered mesoporous carbon (OMC). The resulting iridium‐based OMC materials (Ir‐1, Ir‐2, and Ir‐3) were tested for electrocatalytic water oxidation leading to turnover frequencies (TOFs) of 0.9–1.6 s−1 at an overpotential of 300 mV under acidic conditions. The stability of the materials is demonstrated by electrochemical cycling and X‐ray absorption spectroscopy analysis before and after catalysis. Theoretical studies on the interactions between the molecular complexes and the OMC support provide insight onto the noncovalent binding and are in agreement with the experimental loadings.

Selective Oxidation of Benzyl Alcohol with Oxygen Catalyzed by Vanadia Supported on Nitrogen-Containing Ordered Mesoporous Carbon Materials

Selective Oxidation of Benzyl Alcohol with Oxygen Catalyzed by Vanadia Supported on Nitrogen-Containing Ordered Mesoporous Carbon Materials

Molecular sieving of linear and branched C6 alkanes by tannin-derived carbons

Two micro-mesoporous carbons (MMCs): a disordered mesoporous carbon (DMC) and an ordered mesoporous carbon (OMC), synthesized by an easy, low-cost, and green method are proposed as efficient hydrocarbon sieves for the separation of C6 isomers: n-hexane (nHEX), 2-methylpenthane (2 MP) and 2,2-dimethylbutane (22DMB). Their textural characterization reveals a highly interconnected pore network within the DMC, while a reverse hierarchy of ordered mesopores only accessible through narrow micropores is found in the OMC. The pore texture strongly affects their adsorption performance by kinetic and molecular sieving effects; the narrow constrictions in the OMC allow adsorption of nHEX and partially 2 MP but not 22DMB, whereas the highly connected pore network of DMC allows adsorption of the three isomers. Multi-component adsorption isotherms calculated from the single-component experimental results by ideal adsorbed solution theory (IAST) demonstrates that the OMC material has a remarkably high selectivity for the adsorption of nHEX and nHEX + 2 MP from binary and ternary mixtures, respectively. To the best of the authors’ knowledge, such behavior has never been reported so far for carbon materials. Hence, this study shows that tannin-derived MMCs have great potential to be used as an eco-friendly and low-cost alternative for the selective separation of di-branched C6 isomers.

CdZnSeS quantum dots condensed with ordered mesoporous carbon for high-sensitive electrochemiluminescence detection of hydrogen peroxide in live cells

The accurate and rapid determination of hydrogen peroxide (H2O2) levels is of great significance because of the far-ranging impacts of H2O2 homeostasis on human health. In this work, we developed an enhanced electrochemiluminescence (ECL) biosensor based on CdZnSeS quantum dots (QDs) condensed with ordered mesoporous carbon (OMC) for high-sensitive detection of H2O2 in live cells. Benefiting from the combination of QDs with the highly conductive OMC materials, the prepared ECL biosensor exhibited outstanding ECL signal. We then assessed the analytical performance of the ECL biosensor for H2O2 detection, and found that the biosensor possessed low detection limit, wide linear range, desirable selectivity, and long-time stability. By the detection of H2O2 in different live cells, the ECL biosensor platform shows its potential for reliable and sensitive H2O2 detection in diagnostic applications and physiological research.

Cl2 Adsorption and Desorption over Ordered Mesoporous Carbon Materials as an Indicator for Catalytic Phosgene Formation

AbstractThe presented work evaluates the implementation of adsorption and desorption experiments with Cl2 over carbon materials towards the development of more active and stable catalysts for industrial phosgene synthesis. By using a soft templating method as a tool, ordered mesoporous carbon materials with tunable porosity, surface area, and degree of graphitization were synthesized and utilized as model system. The Cl2 adsorption/desorption properties of these materials were studied and compared to commercial activated carbon. To draw correlations between Cl2 adsorption/desorption behavior and catalytic performance, the materials were further tested in the phosgene formation in a plug flow reactor. However, the chemical reaction of Cl2 with carbon during the adsorption/desorption experiment hinders a direct correlation.

On the Removal of the Cr(VI) in Water by an Ordered Mesoporous Carbon Material: Kinetic and Isotherm Studies

In this work, an ordered mesoporous carbon material CMK-3 was synthesized and tested in the adsorption of Cr(VI) in water with an activated carbon material (AC) as the control. Properties of CMK-3 have been characterized by means of Fourier transform infrared spectroscopy, scanning electron microscopy, and transmission electron microscopy. In the adsorption of Cr(VI) in water, the adsorption rate and adsorption capacity of CMK-3 were found to be better than that of AC. A careful study on the adsorption kinetics and isotherms of Cr(VI) on CMK-3 was taken. The adsorption data of Cr(VI) on CMK-3 had been analyzed by pseudo-first-order, pseudo-second-order, particle diffusion, Elovich, Double constant, and Exponential function kinetic models, which revealed that the kinetic adsorption of Cr(VI) on CMK-3 is well accorded with pseudo-second-order kinetic model. The corresponding parameters for each model are obtained. According to the fitting of Langmuir, Freundlich, and Temkin models, the adsorption of Cr(VI) on CMK-3 was well described by Langmuir model to be a single-molecule layer adsorption. The adaptation of the adsorption of Cr(VI) on CMK-3 to Langmuir adsorption model and pseudo-second-order model suggests that the adsorption of Cr(VI) on CMK-3 can be highly affected by its chemical property although its textural properties also can remarkably affect its adsorption behavior.

Impact of Fe deposition on microwave absorption properties of ordered mesoporous carbon flakes

Lightweight ordered mesoporous carbon (OMC) flakes have been successfully synthesized by an evaporation-induced self-assembly route. The highest specific surface area and pore volume of the OMC flakes reach 1727 m2 g−1 and 2.05 cm3 g−1, respectively. The results of the complex permittivity show the OMC/paraffin composites have high dielectric loss in the frequency range of 2–18 GHz. In order to enhance the microwave absorption properties of the OMC materials, an electroless plating method is exploited to deposit Fe particles on the OMC flakes. Benefiting from the magnetic loss and improved impedance characteristic, the OMC/Fe composites display excellent microwave absorption properties. The minimum reflection loss of the OMC-700-Fe composite reaches − 65.3 dB at 10.1 GHz and the absorption bandwidth < − 10 dB is up to 4.7 GHz (8.7–12.4 GHz) with the absorbing thickness of 2.5 mm. When the thickness is from 1.8 to 5.5 mm, all of the peak values of reflection loss are < − 20 dB. This work provides a new opportunity for the fabrication and design of lightweight microwave absorbers.

Microcolumn lanthanide separation using bis-(2-ethylhexyl) phosphoric acid functionalized ordered mesoporous carbon materials

Adjacent lanthanides are among the most challenging elements to separate, to the extent that current separations materials would benefit from transformative improvement. Ordered mesoporous carbon (OMC) materials are excellent candidates, owing to their small mesh size and uniform morphology. Herein, OMC materials were physisorbed with bis-(2-ethylhexyl) phosphoric acid (HDEHP) and sorption of Eu3+ was investigated under static and dynamic conditions. The HDEHP-OMC materials displayed higher distribution coefficients and loading capacities than current state-of-the-art materials. Using a small, unpressurized column, a separation between Eu3+ and Nd3+ was achieved. Based on these experimental results, HDEHP-OMC have shown potential as a solid phase sorbent for chromatographic, intragroup, lanthanide separations.

A study of the effect of carbon characteristics on capacitive deionization (CDI) performance

In an attempt to improve the capacitive deionization (CDI) performance and develop an efficient CDI electrode material, the effect of carbon characteristics on CDI was investigated. Activated carbon (AC) and ordered mesoporous carbon (OMC) materials synthesized by template method were used for the electrode manufacture. The capacitive deionization performance of AC and OMC based electrodes was investigated and compared. We found that when the specific surface areas of AC materials increased from 712 to 1347m2/g, the electrosorption capacities of AC electrodes increased slightly from 9.43 to 10.14mg/g. The characteristics of OMC materials can be optimized by the adjustment of the mesoporous silica beads template proportion, resulting in a maximum average pore size of 11.35nm and total pore volume of 2.101cm3/g. The optimum electrosorption capacity obtained with OMC4 electrode was 10.83mg/g, which was not only higher than that of AC electrodes, but obviously higher than the values of most carbon-based electrodes in other studies. In conclusion, these results provide important insights into the effect of carbon characteristics on capacitive deionization and suggest that OMC synthesized by template method could be a promising carbon material for the CDI electrode manufacture.

The influence of the pore structure in ordered mesoporous carbon over the formation of Cu species and their catalytic activity towards the methanol oxidative carbonylation

Two ordered mesoporous carbon (OMC) materials with different structures were prepared and used as supports for Cu catalysts. One is prepared by soft-template method (denoted as SOMC), and the other is by hard-template method (donated as HOMC). The microstructures of OMC and Cu/OMC were characterized by XRD, H2-TPR, BET, and TEM. The catalytic activity in oxidative carbonylation of methanol to dimethyl carbonate (DMC) was evaluated in a fixed-bed reactor under atmosphere pressure. Both OMC materials own highly ordered mesostructures, but their pore structure differences have remarkable influences on Cu dispersion, location, valence, as well as the corresponding contents. SOMC has long hollow interiors 3.6 nm in diameter, and most Cu particles are located on its outer surface. By contrast, HOMC is made up of ordered arrays of carbon nanorods, and most Cu particles are homogeneously distributed inside the interconnected 3.6 nm mesoporous among the nanorods. Stronger interaction between Cu particles and HOMC and better Cu dispersion of Cu/HOMC resulted in easier autoreduction of CuO to Cu2O compared with that of Cu/SOMC. As a result, Cu/SOMC exhibited better stability, while Cu/HOMC performed better in terms of the methanol conversion and DMC space–time yield. Besides, increasing the copper loading moderately could be considered as a good option to improve the methanol conversion and space–time yield of DMC.

Rapid and Facile Synthesis of Rod-Like Ordered Mesoporous Carbon Material for Dye Adsorption from Aqueous Solution

A rapid and facile synthesis method for rod-like ordered mesoporous carbon material (OMC) was developed, in which the phenolic resin was used as the carbon source and the precursor solution of rod-like SBA-15 was employed as a hard-template. This new method skipped several processes related to the preparation of SBA-15. The as-synthesized OMC featured a rod morphology with rod lengths of 0.7–1 μm, uniformly sized mesopores (5.1 nm), and a high surface area (795 m2 g–1). Furthermore, the as-synthesized OMC showed excellent capacity for dye adsorption from aqueous solution.

Synthesis of Ordered Mesoporous Carbon Materials by Dry Etching.

A novel synthesis method for ordered mesoporous carbons is presented. The inverse replication of a silica template was achieved using the carbonization of sucrose within mesoporous KIT-6. Instead of liquid acid etching, as in classical nanocasting, a novel dry chlorine etching procedure for template removal is presented for the first time. The resultant ordered mesostructured carbon material outperforms carbons obtained by conventional hard templating with respect to high specific micro- and mesopore volumes (0.6 and 1.6 cm(3) g(-1) , respectively), due to the presence of a hierarchical pore system. A high specific surface area of 1671 m(2) g(-1) was achieved, rendering this synthesis route a highly convenient method to produce ordered mesoporous carbons.

Systematically Controlled Pore System of Ordered Mesoporous Carbons Using Phosphoric Acid as the In situ Generated Catalysts for Carbonization and Activation

We report on a facile synthesis of the ordered mesoporous carbon (OMC) materials with systematically controlled microporosity and mesoporosity simultaneously through the nano‐replication route using phosphoric acid as the acid catalyst and activation agent. The use of phosphoric acid affects the pore structures of OMC materials, such as the formation of numerous micropores by activation of the carbon framework and the enlargement of mesopores by spontaneous phase separation during the carbonization. The mesopore sizes, surface areas, total pore volumes, and micropore volumes of the OMC materials are highly dependent on the phosphoric acid content and can be systematically controlled in the range 3.7–7.5 nm, 1027–2782 m2 g–1, 1.12–3.53 cm3 g–1 and 0.34–0.95 cm3 g–1, respectively. OMC materials with systematically controlled pore structures were successfully synthesized using phosphoric acid as the carbonization catalyst and mesoporous silica materials with cubic Ia3d and 2‐D hexagonal mesostructures as the templates. The phosphoric acid in the synthesis of ordered mesoporous carbon materials acts as the chemical activating agent for micropore generation of the carbon framework and pore‐expanding agent for controlling of mesopore size, in addition to functioning as the acid catalyst. The present synthesis pathway is very useful for preparing OMC materials with tunable mesopore sizes and well‐developed microporosities at the same time.

Synthesis of Polyaniline-Coated Ordered Mesoporous Carbon Composite Electrode Material for Supercapacitor and Its Enhanced Electrochemical Performance.

The polyaniline-coated ordered mesoporous carbon (PCOMC) material was prepared by chemical polymerization of aniline monomers on the ordered mesoporous carbon (OMC). The synthesized PCOMC materials were characterized by scanning electron microscopy, transmission electron microscopy, nitrogen adsorption-desorption isotherms and Fourier infrared spectroscopy. It was demonstrated that the polyaniline was successfully incorporated and well deposited on the external surface and inner pores of the OMC material. Furthermore, the electrochemical performance of the original OMC and PCOMC materials are compared by using cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic charge-discharge tests. The results showed that the electrochemical performance of the OMC material was enhanced after the incorporation of polyaniline. The specific capacitance of PCOMC electrode (813.4 F/g) measured by cyclic voltammetry at the scan rate of 2 mV/s was much higher than that of the OMC electrode (200.9 F/g). The discharge specific capacitance of the PCOMC supercapacitor could be kept at 119.4 F/g when the current density was 5 A/g, indicating its good rate performance even at high charge/discharge current density. Moreover, the PCOMC supercapacitor exhibited long cycling stability with the capacitance retention remained 77% after 3500 cycles.