Pore Structure Of Porous Carbons Research Articles

Solvothermal synthesis of CuS nanosheets loaded porous carbon electrode composites for high performance supercapacitors

In this work, an electrode composite (CuS-NPC) for supercapacitors was synthesized by loading hexagonal nano-sheeted copper sulfide onto porous carbon through a solvothermal reaction using thiourea and copper acetate as the sulfur and copper sources, respectively. The synergistic effect of nanoscale copper sulfide sheet and hierarchical pore structure of porous carbon with high surface area achieves excellent capacitive performance in electrochemical reactions. CuS-NPC exhibited a large specific capacitance of 1298.7F g−1 at current density of 0.5 A/g and 766.3F g−1 at current density of 10 A/g, revealing that the electrode composite of copper sulfide and porous carbon have a great prospect as a supercapacitor electrode material.

Enhancement of CH4/N2 separation capacity of coal-based porous carbons via hydrothermal coupled KOH activation

The separation of CH4 and N2 is an important technology for the effective utilization of low-concentration CBM. To improve CH4/N2 separation properties of coal-based porous carbons, Shaanxi long-flame coal was hydrothermally treated followed by KOH activation for the preparation of porous carbons. The impact of hydrothermal treatment on the pore structure and CH4/N2 separation properties of porous carbons was investigated. The results show that hydrothermal decomposes the macromolecular structure of coal, which enlarges the pore size of the raw coal and facilitates the KOH penetrate deeper into the coal particles. Meanwhile, more release of methylene/methyl groups and in-stiu growth of carbon nanotubes develop the pore structure during the activation process of treated coal. The pore structure of porous carbons can be precisely controlled by adjusting the water-coal ratio in the hydrothermal process. Among them, C-TC1.25 shows a 22% increase in CH4 adsorption capacity over C-RC, which is mainly due to a significant increase in the micropore volume at 0.5–1.0 nm and generation of carbon nanotubes as gas transport channels. At 298 K and 101 kPa, C-TC1.25 exhibits a CH4 adsorption capacity reaching 1.72 mmol/g, which surpasses that of most known adsorbents, while the IAST selectivity is as high as 5.5. The breakthrough experiment confirms that the porous carbons effectively enable separation of CH4/N2 mixed gas. Kinetic studies show the CH4 adsorption process on C-TC1.25 conform to the pseudo-first-order model and exhibit surface-attached physical adsorption.

Sustainable preparation of hierarchical porous carbon from discarded shells of crustaceans for efficient CO2 capture

The improved CO2 adsorption capacity and selectivity is the focus of research on the carbon-based CO2 adsorbent, while nitrogen-containing groups on the surface of adsorbent have an important effect on the CO2 adsorption. In this study, nitrogen self-doped hierarchical porous carbon was prepared from three kinds of crustacean shells, namely, hairy crab shell, crayfish shell and greasyback shrimp shell. It revealed that the pore structure of porous carbon can be regulated well with the varied activation temperature and the amount of KOH. With the favorable activation temperature of 800℃ and the mass ratio of activator to carbon (A/C) of 1:1, the obtained porous carbon with different carbon precursors exhibited relatively high specific surface area (1430.63–1734.64 m2/g), large pore volume (0.70–1.48 cm3/g) and developed pore-size distribution. Consequently, among the three kinds of hierarchical porous carbon tested, that prepared form greasyback shrimp displayed the excellent CO2 adsorption of 5.144 and 4.325 mmol/g at 1 bar, 273 K and 298 K and the highest CO2/N2 selectivity was observed of 32.32, attributed to the volume of mesopore and micropore and the type of nitrogen-containing groups. The effects of nitrogen-containing groups in porous carbon on the CO2 adsorption and CO2/N2 selectivity were analyzed, and it revealed that the CO2/N2 selectivity of porous carbon was positively correlated with pyrrolic N. In conclusion, the porous structures and nitrogen-containing groups of porous carbons both contribute to the CO2 adsorption and selectivity. The porous carbon with well recycling performance in this study presented a practical application prospect.

Pore structure regulation of hierarchical porous agaric-derived carbon via boric acid activation for supercapacitors

The development of sustainable carbon materials from biomass for electric double-layer supercapacitors is a promising solution to alleviate energy and environmental pressures. The electrochemical performance of biomass-derived carbon materials is greatly affected by their hierarchical porous structure. In general, the pore structure of biomass-derived carbon activated using chemical method is dominated by micropores with few mesopores. This hinders the transmission of electrolyte ions, thus limiting the electrochemical properties. Here we have designed a green unique boric acid-assisted method to synthesize hierarchical porous agaric-derived carbon. Benefiting from the unique hygroscopic recovery characteristics of agaric, boric acid can enter the interior of the agaric and act as a novel activator to effectively adjust the pore structure of porous carbon. During the carbonization process, the melted boron oxide with high viscosity and excellent wetting properties adheres to the agaric matrix as a template, which plays a key factor for increasing the mesopores (<4 nm) and promoting ions transport. The synthesized porous carbon has a high specific surface area (2279.5 cm 2 g −1 ), more reasonable hierarchical porous structure, abundant nitrogen atom doping (4.69 at.%) and high capacitance (502 F g −1 @ 0.5 A g −1 ). The symmetric supercapacitor tested in 1 M Na 2 SO 4 electrolyte has excellent performances. This optimization strategy provides a new idea to design more reasonable hierarchical porous biomass-derived carbon materials. • Synthesis of agaric-derived carbon using a green method of boric acid-assisted • The etching of boric acid increases pores in 1–4 nm. • Superior design of hierarchically porous structure promotes ions transport. • N-doped agaric-derived carbon has an excellent specific capacitance of 502 F g −1 .

Construction of embedded heterostructures in biomass-derived carbon frameworks for enhancing electromagnetic wave absorption

To improve multiple heterointerface coupling efficiencies and efficiently engineer the pore structure of porous carbon, a kind of magnetic cobalt nanoparticles embedded porous carbon framework, derived from economical biomass, was designed in the present study. The resulting magnetic embedded porous carbon framework showed exceptional dielectric responses and a significant polarization effect because of the higher contact surface utilization than the ordinary loaded structure. The effective absorbing bandwidth covers 6.6 GHz with a thickness of 2.3 mm, indicating its capacity to address the increasingly problematic electromagnetic (EM) pollution issue. Meanwhile, the magnetic embedded structure with the carbon framework could protect the embedded particles from common corrosion issues, even after a long time environmental adaptability assessment in the lab and faintly acid condition. This work highlights a potential strategy for the design and synthesis of high-performance carbonaceous EM absorbers.

Enhance pore structure of cyanobacteria-based porous carbon by polypropylene to improve adsorption capacity of methylene blue

Porous carbon obtained by co-pyrolysis of plastic and biomass has received a lot of attention due to its excellent adsorption properties, and the pore structure plays an essential role in adsorption performance, however, the pore structure is still not well understood. Herein, we synthesized cyanobacteria-based porous carbon derived from cyanobacteria and polypropylene plastic by one-step method. CPC-800–30% exhibited a high BET surface area (2140 m2/g), pore volume up to 1.44 cm3/g. PP not only improved the pore structure of porous carbon, but also enriched the types of functional groups, such as O–H, N–H, C=O, and –CH, due to dehydroxylation or amino group decreased, resulting in the hydrogen radicals increased, hence PP had positive effect for biomass during co-pyrolysis. Meanwhile, CPC-800–30% showed excellent methylene blue (MB) adsorption capacity (667 mg/g). This work provided a new strategy for enhancing porous carbon structure via using PP as additive.

Porous carbon prepared via combustion and acid treatment as flexible zinc-ion capacitor electrode material

To meet the requirements for high energy/power density, safety and flexibility of wearable electronic devices simultaneously, a solid-state zinc-ion capacitor (ZIC) is assembled by integrating zinc nanosheets anode and porous carbon cathode with gelatin gel as electrolyte. Herein, the oxygen-enriched three-dimensional porous carbon has been synthesized as cathode of ZIC via a facile combustion and sequential acid-treatment process. Taking advantages of the rich oxygen-containing functional groups to provide pseudocapacitance and the specific pore structure of porous carbon to endow fast electrochemical kinetics of cathode, the assembled ZIC could deliver the superb specific capacity of 132.7 mA h g−1, excellent energy density of 82.36 W h kg−1 and superior cycling stability with 87.6% capacity retention over 10,000 cycles at a current density of 1.0 A g−1. Impressively, the assembled solid-state ZIC based on OPC is flexible enough to withstand various deformations including bending and twisting at large angles, which are promising to be applied in portable electronics.

Consistent preparation, chemical stability and thermal properties of a shape-stabilized porous carbon/paraffin phase change materials

Abstract In this study, tin tetrachloride and sodium polyacrylate were combined in a ratio of 5:14 to control the preparation of porous carbon materials using a template method. Then, paraffin was used as the organic phase change materials (PCMs), porous carbon was used as the support material, and four proportions of paraffin/porous carbon shape-stabilized PCMs were prepared by mixed grinding - heating method. Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR) and laser Raman spectroscopy (LRS) results showed that paraffin was adsorbed by the pore structure of porous carbon. X-ray diffraction (XRD), LRS and FT-IR analyses indicated that the shape-stabilized PCMs is chemically stable. Differential scanning calorimetry (DSC) showed that the PCMs has a fusion enthalpy of 35 J/g, and the thermogravimetric analyser (TG) showed that the shape-stabilized PCMs has a stable thermal performance. Finally, porous carbon can improve the phase transition rate of the shaped-stabilized PCMs.

Porous Carbons Derived from Desilication Treatment and Mixed Alkali Activation of Rice Husk Char for Supercapacitors

ABSTRACT Porous carbons with micro-meso hierarchical porous structure derived from rice husk char were first prepared by desilication treatment and mixed alkali activation. The as-obtained porous carbons (Na-K/rRHC800) exhibited a well-developed hierarchical porous carbon with a high specific surface area of 3046 m2 g−1 and numerous interconnected pores with a large pore volume up to 1.70 cm3 g−1 composed of micro-, meso-, and macropores, as well as high graphitization degree. In addition, the Na-K/rRHC800 electrode displayed a high specific capacitance of 312.0 F g−1 at the current density of 0.2 A g−1, an excellent cycling stability (retention of 92.6% after 10,000 cycles) and energy density of 10.8 Wh kg−1 in 6 M KOH. The results indicated that the facile preparation route shows great ease in controlling the pore structure of porous carbons derived from a green and sustainable feedstock of rice husk char for supercapacitor application. Furthermore, the results also improved the perspectives for the economy of the full-scale valorization of rice husk by fast pyrolysis.

Pore structure control of porous carbon obtained from phenol formaldehyde resin and ethylene glycol: the effect of H3BO3 on the pore structure.

Boric acid was used as a source of complexing agent to change phase separation kinetics and dynamics of the resin-glycol system to regulate the pore structure of porous carbon. The results show that the addition of H3BO3 in the resin mixtures can change the polymerization dynamics during curing of resin-glycol mixtures. For the complexation of H3BO3 to diols, the size of the ethylene glycol-rich phase produced during the curing of the resin mixture increase with the increase of the content of H3BO3. Similarly, the pore size of porous carbon after pyrolysis increases with the increase of H3BO3 content. The average pore size of resulting porous carbon can be regulated in the range from 15 to 2754 nm. These results reveal that H3BO3 exhibited obvious effects in changing the pore structure of resin-glycol system during pyrolysis.

Oxygen-Rich Porous Carbon Derived from Biomass for Mercury Removal: An Experimental and Theoretical Study.

A porous carbon was synthesized by the combination of freeze-drying and CO2 activation from starch. Nonthermal plasma was employed to quickly produce oxygen functional groups on a porous carbon surface. The plasma treatment has a negligible effect on the textural properties of the porous carbon. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy analyses suggested that the plasma treatment significantly increased the amount and promoted the evolution of oxygen groups on surface. The unique pore structure of porous carbon was proven favorable to effective oxygen loading. The elemental mercury (Hg0) adsorption ability of the oxygen enriched porous carbon was tested. The results indicated that the oxygen-rich porous carbon constitutes an effective sorbent for Hg0 removal. The excellent textural properties, surface atomic oxygen concentration, and the type of oxygen group are the three key factors for realizing high Hg0 removal performance. Density functional calculations were performed to understand the effect of oxygen groups on Hg0 adsorption. Carbonyl and ester groups are beneficial for Hg0 adsorption, whereas epoxy, carboxyl, and hydroxyl groups inhibit Hg0 adsorption. Plasma treatment enhances Hg0 adsorption by increasing the amount of ester and carbonyl groups on surface.

Pore Reorganization of Porous Carbon during Trace Calcium-Catalyzed Coal Activation for Adsorption Applications

Aiming to widely engineering the pore structure of porous carbons to obtain broadened adaptabilities toward various adsorption applications, we propose a catalytic activation strategy by introducin...

Introducing catalytic gasification into chemical activation for the conversion of natural coal into hierarchically porous carbons with broadened pore size for enhanced supercapacitive utilization.

Focusing on engineering the pore structure of porous carbons for enhanced supercapacitive performances, a new type of coal derived hierarchically porous carbon which is synthesized by introducing a catalytic gasification mechanism into an often-utilized chemical activation process is demonstrated. Such a strategy skillfully employs the catalytic effects of the minerals in natural coal on the etching reaction between CO2 molecules and carbon framework, which easily widen the pore size of well-developed micropores, thereby yielding a hierarchical pore configuration with simultaneously high surface area, large pore volume as well as broadened pore size distribution. The enhanced pore development mechanism is elucidated by a series of control experiments and thermogravimetric analysis. Evaluated as supercapacitor electrode materials, the resulting HPC exhibits state-of-the-art supercapacitive performances in both aqueous and non-aqueous electrolytes, particularly the superior rate capabilities, which highlights the favorable role of broadened pore configuration in facilitating electrolyte ion transfer and storage. Combining with the naturally abundant carbon resource and easily-implemented preparation craft, the as-obtained coal transferred hierarchically porous carbons hold great potentials for industrial production and supercapacitor applications.

Effect of FeCl2 on the pore structure of porous carbon obtained from phenol formaldehyde resin and ethylene glycol

Homogeneous porous carbons were obtained from phenolic resin/ethylene glycol resin mixtures based on polymerization-induced phase separation and template method. The effect of FeCl2 content (ωFe) on the pore structure of the porous carbons was systematically investigated. The addition of iron favors the formation of porous pores with large pore size, fine carbon skeleton and uniformly distributed pore structure. With ωFe increasing from 0% to 1%, the average pore size and apparent porosity of the porous carbons increase from 14 to 190 nm and from 25.6% to 63.3%, respectively. Iron ions can be used as a template and catalyst to change the pore structure of porous carbons.

Effect of curing catalyst content on the pore structure of porous carbon obtained from phenolic resin and furfuryl alcohol

Homogeneous porous carbons with narrow pore size distributions have been obtained from phenolic resin/furfuryl alcohol/ethylene glycol resin mixtures based on polymer blend carbonization. The effect of curing catalyst content (wb) on the polymerization process of the resin mixtures and the pore structure of the porous carbons has been systematically investigated. The results show that higher wb results in bigger pore size, thicker carbon skeleton and higher apparent porosity. The morphological and pore structural change of the porous carbons is induced by phase separation dynamics and reaction kinetics change on curing of initial resin compositions, by varying wb in the resin–glycol mixtures. More curing catalyst results in chemical reactions between phenolic resin and furfuryl alcohol occurring at a higher speed and the polymerization degree of the cured bodies increases.

Preparation of Mesoporous Carbon by Phenol Resin Polymerization-dependent Phase Separation and Pyrolysis

Porous carbon was prepared by technique of phenol resin polymerization-dependent phase separation and pyrolysis.The influence of catalyst amount on pore structure of porous carbon was investigated.The results show that porous carbons with average pore size of ca.40nm are obtained. The apparent porosity increases with increasing amount of catalyst.When the catalyst amount is 15%, apparent porosity of the porous carbon reaches 54.3%.Moreover,the carbon skeletons of the porous carbons become finer with high amount of catalyst.Volume shrinkage and gel time play important roles in changing the pore structure of porous carbons,for the porous carbons with high amount of catalyst have less shrinkage and shorter gel time during the curing.

Surface Chemical Functional Groups Modification of Porous Carbon

The surface chemistry and pore structure of porous carbons determine its application. The surface chemistry could be modified by various methods, such as, acid treatment, oxidization, ammonization, plasma, microwave treatment, and so on. In this paper, the modification methods were illustrated and compared, some new methods also reviewed. The surface chemical functional groups were determined by the treatment methods, the amminization could increase its basic property while the oxidization commonly improved its acids. In the end, the commonly characterization methods were also mentioned. Some interesting patents are also discussed in this article. Keywords: Porous carbon, surface chemical groups, modification, characterization

Evaluation of Methods for Determining the Pore Size Distribution and Pore-Network Connectivity of Porous Carbons

The pore size distribution (PSD) and the pore-network connectivity of a porous material determine its properties in applications such as gas storage, adsorptive separations, and catalysis. Methods for the characterization of the pore structure of porous carbons are widely used, but the relationship between the structural parameters measured and the real structure of the material is not yet clear. We have evaluated two widely used and powerful characterization methods based on adsorption measurements by applying the methods to a model carbon which captures the essential characteristics of real carbons but (unlike a real material) has a structure that is completely known. We used three species (CH4, CF4, and SF6) as adsorptives and analyzed the results using an intersecting capillaries model (ICM) which was modeled using a combination of Monte Carlo simulation and percolation theory to obtain the PSD and the pore-network connectivity. There was broad agreement between the PSDs measured using the ICM and the geometric PSD of the model carbon, as well as some systematic differences which are interpreted in terms of the pore structure of the carbon. The measured PSD and connectivity are shown to be able to predict adsorption in the model carbon, supporting the use of the ICM to characterize real porous carbons.

Study on Pore Structure of Porous Carbons by Small-Angle X-ray Scattering

Study on Pore Structure of Porous Carbons by Small-Angle X-ray Scattering