Micro-mesoporous Carbon Research Articles

Preparation of micro-mesoporous carbon from seawater-impregnated sawdust by low temperature one-step CO2 activation for adsorption of oxytetracycline

Porous carbons (PCs) were prepared from seawater (SW)-impregnated sawdust (SD) by CO2 activation at 700 °C. The preparation process was investigated on-line by thermogravimetric analyzer coupled with FTIR (TG-FTIR). PCs were characterized by N2-adsorption/desorption and Fourier transform infrared spectroscopy. The adsorption abilities of PCs for oxytetracycline (OTC) were compared and the adsorption isotherms of OTC on the optimum sample were studied. Results showed that SW impregnation led to the release of more CO from SD at 700 °C, indicating a higher degree of CO2 activation, thus a 81% higher BET surface area (SBET) can be achieved under the same activation condition. Mesopore volume of PC increased from 0.089 to 0.301 cm3 g−1 with the activation time increasing from 5 to 60 min. PC obtained after 60-min activation with a SBET of 490 m2 g−1 and an average pore diameter of 3.78 nm had the highest adsorption ability for OTC. Its adsorption equilibrium data for OTC followed Langmuir model with a maximum monolayer adsorption capacity up to 100 mg g−1.

Rational design of well-dispersed ultrafine CoS2 nanocrystals in micro–mesoporous carbon spheres with a synergistic effect for high-performance lithium–sulfur batteries

Micro–mesoporous carbon (MMC) embedded with well-dispersed ultrafine CoS2 (uCoS2) nanocrystals as an efficient sulfur host is prepared by a new method. As a result, a S/uCoS2@MMC cathode exhibits outstanding cycling stability and rate performance.

Removal of orange II from aqueous solutions using micro-mesoporous carbon materials: kinetic and equilibrium studies

Removal of orange II from aqueous solutions using micro-mesoporous carbon materials: kinetic and equilibrium studies

Encapsulating Red Phosphorus in Ultralarge Pore Volume Hierarchical Porous Carbon Nanospheres for Lithium/Sodium-Ion Half/Full Batteries.

Red phosphorus (P) has been recognized as a promising material for lithium/sodium-ion batteries (LIBs/SIBs) because of their high theoretical capacity. However, tremendous volume variation and low conductivity limit its widespread applications. Hence, we design and synthesize uniformly distributed honeycomb-like hierarchical micro-mesoporous carbon nanospheres (HHPCNSs) with ultralarge pore volume (3.258 cm3 g-1) on a large scale through a facile way. The large pore volume provides enough space for loading of P and the expansion of P, and the uniform distribution of the micro-mesopores enables the red P to load uniformly. The resulting HHPCNSs/P composite exhibits extremely high capacity (2463.8 and 2367.6 mA h g-1 at 0.1 A g-1 for LIBs and SIBs, respectively), splendid rate performance (842.2 and 831.1 mA h g-1 at 10 A g-1 for LIBs and SIBs, respectively) and superior cycling stability (1201.6 and 938.4 mA h g-1 at 2 and 5 A g-1 after 1000 cycles for LIBs and 1269.4 and 861.8 mA h g-1 at 2 and 5 A g-1 after 1000 cycles for SIBs, respectively). More importantly, when coupled with LiFePO4 and Na3V2(PO4)3 cathode, lithium/sodium-ion full batteries display high capacity and superior rate and cycling performances, revealing the practicability of the HHPCNSs/P composite. The exceptional electrochemical performance is caused by the honeycomb-like carbon network with ultralarge pore volume, uniformly distributed hierarchical micro-mesoporous nanostructure, outstanding electronic conductivity, and excellent nanostructural stability, which is much better than currently reported P/C materials for both LIBs and SIBs.

High benzene adsorption capacity of micro-mesoporous carbon spheres prepared from XAD-4 resin beads with pores protected effectively by silica

The aim of this work was to prepare micro-mesoporous carbon spheres with high specific surface area and large volume of mesopores from porous styrene-co-divinylbenzene ion exchange resin Amberlite XAD-4 beads. Prior to the carbonization step, the mesoporous resin beads were protected by silica formed via impregnation of tetraethylorthosilicate followed by its hydrolysis and condensation. This was essential to obtain highly porous carbon spheres after silica removal that featured the specific surface area up to 1050 m2 g−1 and total pore volume up to 1.35 cm3 g−1. Additional CO2 activation resulted in micro-mesoporous carbon spheres and consequently boosted their adsorption capacity for benzene up to 21–24 mmol g−1 at 20 °C and relative pressure close to unity. Moreover, carbon dioxide adsorption properties of the samples were studied, and the highest uptake of 4.5 mmol g−1 at 0 °C and 1 bar pressure was obtained for the activated carbon. Our findings indicate that the activated carbon spheres exhibit a great potential for capture benzene and related volatile organic compounds.

Synthesis of carbon coated Fe3O4 grown on graphene as effective sulfur-host materials for advanced lithium/sulfur battery

Lithium/sulfur battery (LSB) is considered as one of the most promising battery systems due to its high energy density of 2600 Wh kg−1. Nevertheless, the LSB suffers from some inherent problems that impede its practical application. To circumvent these problems, we grow carbon-coated ferroferric oxide (Fe3O4) nanoparticles on graphene (Fe3O4@C-G) as an effective sulfur host for LSB via a facile hydrothermal method followed by calcination. Highly conductive graphene is utilized to homogeneously deposit the carbon-coated Fe3O4 nanoparticles (Fe3O4@C), which enable rapid and steady long-distance electron transport. Moreover, the carbon coated particles of Fe3O4@C exhibit a developed micro-mesoporous structure, which not only provide space for sulfur loading to prepare a composite Sulfur/carbon-coated Fe3O4 nanoparticles on graphene (S/Fe3O4@C-G) cathode, but also provide channels for the interaction between Fe3O4 and lithium polysulfides. Furthermore, a strong chemical affinity of Fe3O4 nanoparticles coated by micro-mesoporous carbon layers towards polysulfides can be strengthened through the polar-polar interaction. Owning these advantages, the S/Fe3O4@C-G composite cathode deliver a high initial capacity of 1425 mAh g−1 at 0.2 C and maintain a capacity of 1102 mAh g−1 after 100 cycles.

General Synthesis Approach for Hierarchically Porous Materials via Reverse Microemulsion System

A well-ordered hierarchically micromesoporous carbon has been successfully fabricated in a reverse microemulsion system via a heated evaporation-induced self-assembly (HISA) method. An additional heat accelerates the rate of the solvent evaporation for accomplishing the self-assembly process of the surfactant. Interestingly, it only takes about 7 min for the preparation of polymer by using this facile HISA. The tedious prepolymerization process between phenol and resorcinol can be saved by directly mixing them together in the system, and the subsequent thermal consolidation process at 100 °C for about 24 h in the usual method can also be eliminated. Meanwhile, evaporation-induced self-assembly (EISA) and hydrothermal (HT) approaches have also been employed to prepare the porous carbon in F127/MMA reverse microemulsion. Hierarchically porous carbon materials prepared by using reverse microemulsion as the electrode of supercapacitors exhibit an excellent performance in electrochemical application. Hierarchi...

Meso-microporous carbon nanofibers with in-situ embedded Co nanoparticles for catalytic oxidization of azo dyes

To meet the current challenges in the treatment of azo dye wastewater by advanced oxidation processes (AOPs), meso-microporous carbon nanofiber with in-situ embedded Co nanoparticles (Co/P-CNF) is developed by electrospinning Co salt/polyvinylpyrrolidone (PVP)/polyacrylonitrile (PAN) solution followed by carbonization process. The use of PVP as pore-forming agent in PAN solution promotes the formation of meso-microporous structure of P-CNF in carbonization phase, achieving micropore surface area of 98 m2 g−1 and mesopore surface area of 214 m2 g−1 by BET analysis. The heterogeneous catalytic performance of synthesized Co/P-CNF is evaluated by the degradation of Acid Red 1 (AR1) with peroxymonosulfate (PMS). Complete removal of AR1 of 50 × 10−6 M is achieved within 6 min by Co/P-CNF and PMS system. The superior catalytic performance of Co/P-CNF is attributed to both the nanofibrous morphology and meso-microporous structure due to using the pore-forming agent (PVP), which endow the uniform distribution of Co nanoparticles, favor the exposure of active sites and promote electron and mass transfer. Co/P-CNF not only possesses excellent magnetic property but also has good stability and recyclability, which is desirable for the practical application of the treatment of azo dye wastewater. Co/P-CNF is validated to activate PMS using Co0/Co2+/Co3+ for generating sulfate radicals, hydroxyl radical and singlet oxygen and then degrade AR1. Therefore, the combination of electrospun nanofibrous structure and the use of pore-forming agents is a promising strategy for the preparation of high-performance carbon nanofiber supported catalysts.

Meso-/microporous carbon as an adsorbent for enhanced performance in solid-phase microextraction of chlorobenzenes

There is urgent demand for the design of advanced coating materials for solid-phase microextraction (SPME) for water quality monitoring and assessment because of the global occurrence of chlorobenzenes (CBs). In this study, we proposed a dual-order activation method in which potassium hydroxide is used to modify pre-activated calcium citrate to synthesize a highly developed meso-/microporous carbon (MMC). The as-obtained MMC presented well-developed porosity with a super-high specific surface area (2638.09 m2 g−1), abundant meso-/micropores (0.5–10 nm), high hydrophobicity, excellent thermal stability (>720 °C), and a partly graphitized structure. As a coating material for headspace-SPME, the MMC-coated fiber exhibited outstanding extraction capability for CBs (up to 48.5 times higher than that of commercial fibers), which may be attributed to multiple interactions between the MMC and the pollutants, including size selectivity, micropore filling, π-π stacking and hydrophobicity. Finally, a satisfactory method using an MMC-coated fiber coupled with gas chromatography and electron capture detection was developed with good linearity (1–1000 ng L−1, R2 > 0.9982), high enrichment efficiencies (enrichment factors, 861–7819), low limits of detection (0.003–0.072 ng L−1), excellent repeatability (0.7–5.3%) and reproducibility (1.7–5.1%), and outstanding recoveries (90.18–103.02%) when applied to determine trace CBs in real water samples. These results suggest that MMC is a promising coating material for the SPME of CBs.

Facile and scalable synthesis of micro-mesoporous carbon/magnesium oxide/sulfur composite for lithium-sulfur batteries

The construction of efficient conductive porous cathodes with prevention of polysulfides dissolution is essential for useful application of lithium-sulfur batteries. In this work, a micro-mesoporous carbon/magnesium oxide/sulfur composite is developed for lithium-sulfur batteries. The novel micro-mesoporous carbon powders grown on diatomite substrates by chemical vapor deposition provide efficient pathways for electron migration in the cathode and alleviate the structural failure caused by volume expansion. Our combined experimental and simulated results confirm that the synergistic magnesium oxides play an important role in anchoring lithium polysulfides. We find in this study that micro-mesoporous carbon/magnesium oxide/sulfur composite with 10 wt% magnesium oxide shows the best cycle and rate performance: a) the battery exhibits an initial specific capacity of 1143 mAh g−1 at 0.2 C and a reversible capacity of 592 mAh g−1 after 500 cycles with an average of 99% columbic efficiency. b) A reversible discharge capacity of 664 mAh g−1 is achieved after 400 cycles at 2 C which corresponds to a very small capacity decay per cycle ~ 0.065%. c) 90% reversible capacity remains after 200 cycles even under a current density as high as 5 C.

Hierarchical Porous Carbon Derived from Sichuan Pepper for High-Performance Symmetric Supercapacitor with Decent Rate Capability and Cycling Stability.

Hierarchical micro-mesoporous carbon (denoted as HPC-2 in this study) was synthesized by pre-carbonization of biomass Sichuan pepper followed by KOH activation. It possessed well-developed porosity with the specific surface area of 1823.1 m2 g−1 and pore volume of 0.906 cm3 g−1, and exhibited impressive supercapacitive behaviors. For example, the largest specific capacitance of HPC-2 was tested to be ca. 171 F g−1 in a three-electrode setup with outstanding rate capability and stable electrochemical property, whose capacitance retention was near 100% after cycling at rather a high current density of 40 A g−1 for up to 10,000 cycles. Furthermore, a two-electrode symmetric supercapacitor cell of HPC-2//HPC-2 was constructed, which delivered the maximum specific capacitance and energy density of ca. 30 F g−1 and 4.2 Wh kg−1, respectively, had prominent rate performance and cycling stability with negligible capacitance decay after repetitive charge/discharge at a high current density of 10 A g−1 for over 10,000 cycles. Such electrochemical properties of HPC-2 in both three- and two-electrode systems are superior or comparable to those of a great number of porous biomass carbon reported previously, hence making it a promising candidate for the development of high-performance energy storage devices.

Micro-Mesoporous Carbon Materials Prepared from the Hogweed (Heracleum) Stalks as Electrode Materials for Supercapacitors

The data on carbonization and surface activation of raw hogweed (Heracleum) are presented. The structural and electrochemical properties of thus synthesized carbon materials which can be used as the electrode materials in supercapacitors are studied. The hogweed samples are preliminarily carbonized at 400°C and then activated with potassium hydroxide (KOH) at temperatures of 700, 800, and 900°C in argon atmosphere. According to isotherms of nitrogen adsorption and the BET equation, the specific surface area of samples activated at 700, 800, and 900°C is 913 ± 22, 1215 ± 70, and 1929 ± 99 m2/g, respectively. As the activation temperature increases, the specific surface area and the mesopore volume of samples also increases, whereas the micropore fraction decreases. 1,1-Dimethylpyrrolidinium tetrafluoroborate in acetonitrile was used as an electrolyte. The specific capacitance of samples activated at 700, 800, and 900°C at the current density of 1 A/g is 51 ± 4, 114 ± 2, and 108 ± 3 F/g, respectively. The 40% increase in the specific surface area and the 35% increase in the volume of mesopores results in the increase in the specific capacitance. The further increase in the specific surface area and the volume of mesopores up to 70% does not increase the specific capacitance.

Hierarchical micro-mesoporous carbon prepared from waste cotton textile for lithium-sulfur batteries

As the next generation battery, the lithium-sulfur battery with high theoretical specific capacity and energy density needs to overcome the low practical discharge capacity and the poor cycle performance for the poor conductivity of sulfur and the shuttle effect of polysulfide. In this study, a hierarchical micro-mesoporous carbon (HPC) is designed and synthesized as a sulfur host from the cotton textile with KOH activation at 700 °C to combine the advantages of these two structures, where mesoporous structure can improve the infiltration of electrolyte to act as fast ionic channel and micropores have an excellent ability of binding sulfur. The HPC showed an excellent high specific surface area (2835.47 m2 g−1) and a high pore volume (2.82 cm3 g−1), and the ratio of the mesoporous reaches 57.85%. The sulfur in HPC/S was uniformly distributed in the host structure and no surface crystallization was observed by TEM characterization. Assembled in the lithium-sulfur battery, the cathode mixed with HPC/S and conductive agent delivers an initial discharge capacity of 1577 mAh g−1 at 0.1C, and a reversible capacity of 434.5 mAh g−1 after 300 cycles at the current rate of 1C.

CO2 capture using three-dimensionally ordered micromesoporous carbon

Adsorption of CO2 on three-dimensionally ordered micromesoporous carbon with a spherical pore structure has been studied using gravimetric and manometric analyses. Adsorptive properties were compared with activated carbon and nanostructured carbon materials such as carbon nanotubes, zeolitic-imidazolate framework-derived carbon, carbon nanohorns and ordered mesoporous carbon materials. The regular spherical pores of 14–15 nm diameter with a large pore volume of 3.4 cm3 g−1 provided a very high CO2 adsorption capacity exceeding the compared carbon materials at high gas pressures (≥4 MPa and room temperature). A strong increase in the isosteric heat of CO2 adsorption with increasing surface coverage indicates that high pressure adsorption was predominantly controlled by strong quadrupole moment interactions between CO2 molecules and less intensive interactions of CO2 with the mesoporous surface. Micropores in the walls of the main spherical mesopores, with a pore volume of 0.17 cm3 g−1, provided good CO2 adsorption properties at atmospheric pressure, characterized by rectilinear isotherms and a predominant surface coverage mechanism. Analysis of the strength of CO2 interaction with the carbon adsorbent and a kinetic study of CO2 adsorption revealed excellent CO2 adsorption-desorption reversibility.

In Situ X-ray Photoelectron Spectroscopic and Electrochemical Studies of the Bromide Anions Dissolved in 1-Ethyl-3-Methyl Imidazolium Tetrafluoroborate

Influence of electrode potential on the electrochemical behavior of a 1-ethyl-3-methylimidazolium tetrafluoroborate (EMImBF4) solution containing 5 wt % 1-ethyl-3-methylimidazolium bromide (EMImBr) has been investigated using electrochemical and synchrotron-initiated high-resolution in situ X-ray photoelectron spectroscopy (XPS) methods. Observation of the Br 3d5/2 in situ XPS signal, collected in a 5 wt % EMImBr solution at an EMImBF4–vacuum interface, enabled the detection of the start of the electrooxidation process of the Br− anion to Br3− anion and thereafter to the Br2 at the micro-mesoporous carbon electrode, polarized continuously at the high fixed positive potentials. A new photoelectron peak, corresponding to B–O bond formation in the B 1s in situ XPS spectra at E ≤ −1.17 V, parallel to the start of the electroreduction of the residual water at the micro-mesoporous carbon electrode, was observed and is discussed. The electroreduction of the residual water caused a reduction in the absolute value of binding energy vs. potential plot slope twice to ca. dBE dE−1 = −0.5 eV V−1 at E ≤ −1.17 V for C 1s, N 1s, B 1s, F 1s, and Br 3d5/2 photoelectrons.

Electrical Double Layer Capacitors Based on Steam and CO2-Steam Co-Activated Carbon Electrodes and Ionic Liquid Electrolyte

EDLCs based on micro-mesoporous carbon electrodes prepared from steam and CO2-steam co-activated SiC-CDCs and room-temperature ionic liquid 1-ethyl-3-methylimidazolium tetrafluoroborate as an electrolyte were tested to establish the electrochemical power and energy densities and region of ideal polarizability. Cyclic voltammetry, constant current charge/discharge (CC/CD), electrochemical impedance spectroscopy (EIS) and constant power discharging methods have been applied to establish the electrochemical characteristics of EDLCs completed. The highest capacitance value of 162 F g−1 at 3.6 V has been established by EIS for the SiC-CDC material, which was activated with steam at 1000°C and cleaned with molecular H2. The capacitance values for other materials prepared using the steam activation process at different temperatures were only slightly lower. The calculated coulombic efficiency values from constant current discharge/charge data for all the systems remained within the range from 97.0 to 98.5% and from 99.3 to 100% at current densities 0.1 A g−1 and 1 A g−1, respectively. The coulombic efficiencies calculated from integrated cyclic voltammetry plots varied from 97 to 98 and from 99 to 100% at potential scan rates 5 and 50 mV s−1, respectively, showing that the steam activated SiC-CDC materials are very promising for various high energy density storage/generation applications.

Enhanced Power Performance of Highly Mesoporous Sol-Gel TiC Derived Carbons in Ionic Liquid and Non-Aqueous Electrolyte Based Capacitors

The electrical double layer capacitors (EDLC) based on hierarchical micro-mesoporous sol-gel TiC derived carbon (SgTiC-CDC) electrodes and 1-ethyl-3-methylimidazolium tetrafluoroborate (EtMeImBF4) and 1M Et3MeNBF4 + acetonitrile (AN) as the electrolytes were tested to establish the electrochemical characteristics and region of ideal polarizability. The precursors for the micro-mesoporous carbon electrodes were synthesized via modified sol-gel synthesis process. Compared to traditional titanium carbide derived carbons, where precursor carbide is commercially available, the sol-gel TiC derived hierarchical carbon materials exhibit larger specific density functional theory (DFT) surface areas (up to 1700 m2 g−1) and an unique pore size distribution with more mesopores between 2 and 10 nm. The electrochemical properties of the EDLCs were investigated using the cyclic voltammetry, electrochemical impedance spectroscopy, galvanostatic charge/discharge and constant power discharge methods. The EDLCs demonstrated nearly ideal capacitive behavior even at very high charging/discharging currents (10 A g−1) and cell potential scan rates (500 mV s−1). The EDLCs completed from SgTiC-CDC materials and EtMeImBF4 and Et3MeNBF4 + AN show good energy efficiencies (varying from 93% to 95% at current 1 A g−1) and coulombic efficiency values exceeded 99%. Thus, the EDLCs completed are very promising devices for extremely high power/energy density applications.

Ordered micro-mesoporous carbon from palm oil cooking waste via nanocasting in HZSM-5/SBA-15 composite: Preparation and adsorption studies.

This work reports the preparation of HZSM-5/SBA-15 micro-mesoporous materials with composite structure by mechanosynthesis and their use as templates to micro-mesoporous carbons, with palm oil cooking waste as carbon source. HZSM-5/SBA-15 composites were prepared in different mass proportions (25:75, 50:50 and 75:25) by a mechanosynthetic strategy. The palm oil waste was infiltrated into the template pores by a two-step procedure involving grinding followed by stirring the suspension in an oil solution and carbonization under inert atmosphere. SEM images showed the efficiency of mechanosynthesis for all mass proportions, while textural properties were strongly influenced by the presence of SBA-15. A comparison of 50% HZSM-5/SBA-15 mixture with pristine SBA-15 and uncalcined SBA-15 as carbon templates evidenced that the 50% HZSM-5/SBA-15 mixture lead to the carbon with the highest surface area and pore volume. The resulting carbon material was studied as adsorbent to different dye molecules, including molecules with different charges and sizes. Results revealed that the carbon has a significantly higher affinity for cationic dyes, that the mesopore structure favors high diffusion rates and that the surface groups have a very high affinity for cationic dye molecules.

Insights on palladium decorated nitrogen-doped carbon xerogels for the hydrogen production from formic acid

N-doped carbon xerogels synthesized from melamine-resorcinol-formaldehyde aqueous gels were used as supports for the preparation of Pd-based catalysts for the formic acid dehydrogenation reaction. The effect of the pore texture and nitrogen content of the carbon xerogels on the catalytic activity for the hydrogen production was investigated. It was observed that an appropriate nitrogen doping in a well-defined micro-mesoporous carbon xerogel enables the preparation of Pd catalysts with appreciable catalytic enhancement towards the formic acid dehydrogenation as compared to the N-free counterpart, reaching an initial TOF value of 2014 h−1.

Rice Husk Derived Micro-Mesoporous Carbon Materials as Active Components of Supercapacitor Electrodes

Activated carbon materials (CM) were prepared from rice husk carbonized in the fluidized catalysts bed reactor. Textural characteristics of CM were studied by the adsorption of nitrogen at 77 K. Variation of synthesis conditions (conditions of carbonization and following activation) allowed to obtain materials with specific BET surface area from 440 to 2290 m2/g. Utilization of sodium or potassium carbonates results in the BET surface area up to 1200 m2/g. Activation by hydroxides of sodium or potassium yields the samples with the more developed surface up to 2290 m2/g. Electrochemical properties and capacitive characteristics were examined by cyclic voltammetry and chronopotentiometry in galvanostatic mode in aqueous electrolyte 1 M H2SO4 and ionic liquid BMIMBF4. It was shown, that at low charge/discharge rate (0.2 А/g) gravimetric capacitance depends linearly on specific surface of CM and does not depend on electrolyte nature. Insignificant (in the case of 1 М H2SO4) and significant (in the case of ionic liquid) decrease of specific capacitance is observed at high rates of charge/discharge (2 А/g), which is explained by influence of porous structure.