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In this study, microporous activated carbon was produced from jellyfish-based biomass to capture carbon dioxide (CO 2), toward addressing one of the biggest modern problems. The surface functional groups and porosity of activated carbon derived from jellyfish were investigated according to the activation conditions. It was confirmed that the jellyfish-based porous carbon prepared by NaOH activation comprised many micropores that facilitated CO 2 adsorption under the influence of Na and P present in the microstructure of the jellyfish. In addition, the JFBC-based activated carbon had surface functional groups such as nitrogen, calcium, and magnesium, which facilitated CO 2. The jellyfish-based activated carbon shows very excellent CO 2 adsorption capacity (9.52 mmol/g and 5.18 mmol/g at 273 K and 298 K, respectively) compared to activated carbon prepared from porous carbon-based adsorbents for CO 2 capture. This performance is attributed to the microstructure and various heteroatoms of the jellyfish biochar. Therefore, this study may provide insight into new biomass with competitive adsorption power and without requiring complicated manufacturing steps. [Display omitted] • Synergistic effect of NaOH and Na, P forms micropores internally. • JFBC surface has N, Ca, Mg functional groups, advantageous for CO 2 adsorption. • The microporosity is > 77% with a concentrated distribution of micropores. • CO 2 adsorption capacity can up to 9.52 mmol/g and 5.18 mmol/g at 273 K and 298 K. [ABSTRACT FROM AUTHOR]

Activated carbons (ACs) were modified via e-beam irradiation at various doses for use as an electrode material in electric double-layer capacitors (EDLCs). The chemical compositions of the AC surfaces were largely unchanged by the e-beam irradiation. The ACs treated with the e-beam at radiation doses of 200 kGy exhibited higher nanocrystallinity than the untreated ACs. The specific surface areas and pore volumes of the e-beam irradiated ACs were also higher than those of the untreated ACs. These results were attributed to the transformation and degradation of the nanocrystallinity of the AC surfaces due to the e-beam irradiation. The specific capacitance of the ACs treated with the e-beam at radiation doses of 200 kGy increased by 24% compared with the untreated ACs, and the charge transfer resistance of the ACs was decreased by the e-beam irradiation. The enhancement of the electrochemical properties of the e-beam irradiated ACs can be attributed to an increase in their specific surface area and surface crystallinity. [ABSTRACT FROM AUTHOR]

Abstract: Hydrogen adsorption on activated carbons was investigated in the present works up to 100bars at 298K. Coconut-shell was activated by potassium hydroxide, resulting in activated carbons with different porosities. All of prepared activated carbons are microporous and show the same adsorption properties. The complete reversibility and fast kinetics of hydrogen adsorption show that most of adsorbed quantity is due to physical adsorption. A linear relationship between hydrogen adsorption capacity and pressure is obtained for the all samples regardless of their porosities. Hydrogen adsorption capacities are linear function of porosities such as specific surface area, micropore surface area, total pore volume, and micropore volume. The maximum hydrogen adsorption capacity of 0.85wt.% at 100bars, 298K is obtained in these materials. [Copyright &y& Elsevier]

In this study, a CuO support was successfully introduced onto an activated carbon fiber (ACF) surface by sputtering and was chemically formed by growth and aggregation to improve the active sites for high-efficiency SO 2 gas adsorption. The gas adsorption mechanism was studied based on the pore structure, gas adsorption behaviour and electrical resistance of the ACF during gas adsorption. This process improved two steps of the adsorption mechanism. First, the pore structure significantly influenced the gas adsorption properties. Second, the CuO support attracted the target gas to the surface of the ACFs through copper metal groups. The adsorption properties for SO 2 gas were improved by the electrical resistance of the ACFs through the electron hopping effect of the adsorbed polarized SO 2 molecules. [ABSTRACT FROM AUTHOR]

In this study, a high-efficiency SO 2 adsorbent was manufactured using activated carbon fibers (ACFs) into which a Cu supporter was introduced. Carbon fibers were obtained by subjecting a Lyocell fiber to a flame-retardant treatment and carbonization process. A high specific surface area and a uniform microporous structure were obtained using KOH activation to improve the SO 2 adsorptivity. After activation, a solution of Cu(NO 3 ) 2 ·3H 2 O was used as a chemical agent to impregnate the Cu supporter. As a result, we observed micropores and mesopores in the ACFs and even diffusion of the Cu supporter over the surfaces of the ACFs. After introducing the Cu supporter, the specific surface area and the percentage of micropores increased by 15% or more, and the SO 2 adsorptivity increased by 180% or more in comparison to the ACFs without Cu supporter. The SO 2 adsorptivity is thought to have been improved as a result of the synergetic effect of physical adsorption by the micropores and mesopores, the specific surface area developed by the effect of the transition metal while introducing the Cu supporter, and the chemical adsorption reaction of SO 2 gas by the Cu supporter. [ABSTRACT FROM AUTHOR]

Abstract: In this study, we investigated the role of fluorination in improving the electrochemical properties of activated carbon nanofiber (ACNF) electrodes. The ACNFs were prepared with various textural properties and then fluorinated. The electrochemical properties of the resulting ACNFs were subsequently evaluated to investigate the effect of the fluorination of the prepared ACNFs with various textural properties on the electrochemical properties. The specific capacitances of the ACNF electrodes increased by 15.8–47.3% after fluorination, although the specific surface area and the total pore volume decreased significantly; these results suggest that the introduction of C F functional groups onto the ACNF surface was more important than the induction of changes in the textural properties of the ACNF samples with respect to improving the electrochemical properties of the ACNF electrodes. The retained capacitances of the ACNF electrodes also increased 2–12% after fluorination, although the etching effect of the fluorination significantly collapsed the mesopores; these results suggest that the C F functional groups were electrochemically active even at a high scan rate. [Copyright &y& Elsevier]

Abstract: In this study, the capacity of hydrogen storage was evaluated by using electrospun activated carbon fibers prepared by electrospinning and chemical activation based on the comparison with other carbon materials such as active carbon, single walled carbon nanotube, and graphite. For an improved hydrogen storage system, the optimized conditions of carbon materials were investigated with studying their specific surface area, pore volume, size, and shape. The hydrogen adsorption capacity of chemically activated electrospun carbon fiber itself is better than that of other porous carbon materials. This is attributed to the optimized pore structure of electrospun activated carbon fibers that might provide better sites for hydrogen adsorption than other carbon materials. [Copyright &y& Elsevier]

Abstract: In this work, copper nanoparticles were plated onto the surfaces of activated carbon fibers (ACFs) in order to investigate the effects of their presence on the high pressure hydrogen-storage behaviors of the resultant Cu/ACFs, as studied by PCT apparatus at 100atm and 298K. The Cu/ACFs’ pore structures and total pore volumes were analyzed by reference to adsorption isotherms, and their chemical composition and surface morphologies were characterized using an energy-dispersive X-ray spectrometer (EDS) and a scanning electron microscope (SEM), respectively. In the experimental result, the specific surface area and total pore volume decreased with increasing electroplating time. However, the hydrogen-storage capacity was enhanced in the presence of Cu nanoparticles for Cu-10 and Cu-30 samples, and then began to decline. These results indicated that the surface properties were decreased by the Cu nanoparticles, but that the hydrogen-storage capacity was increased by the modified spill over of hydrogen molecules into the carbon structures. [Copyright &y& Elsevier]

Abstract: Mesoporous activated carbon samples were prepared from electrospun PAN-based carbon fibers using physical activation with silica. Textural characterization was performed using nitrogen adsorption at 77 K. The BET specific surface area and pore size distribution of silica activated carbon materials were investigated. According to the increment of silica, BET specific surface area was increased about thirty times and it was found that silica activated carbon materials were highly mesoporous by studying pore surface distribution and pore volume distribution. Surface morphology of silica activated carbon materials were observed by SEM images. The spherical typed carbon materials were investigated. The diameter of spherical typed carbon materials was increased in proportional of the increment of silica. [Copyright &y& Elsevier]

Abstract C F bonds are introduced on activated carbon (AC) by fluorination, and the resulting fluorinated AC (FAC) is fabricated into electrodes to investigate the effect of C F bonds on the capacitive deionization (CDI) performance. The concentration of C F bonds on the AC surface is a high as 19.5%, but the specific surface area of FAC is reduced by etching of the pore walls. Nevertheless, the specific capacitance of FAC is up to 30% higher than that of raw AC (RAC). The negative surface charge formed by the electronegativity difference between carbon and fluorine causes an increase in the open circuit potential (OCP) of the CDI cell, which results in a higher charge efficiency. Therefore, the specific electrosorption capacity of FAC is 16.5 mg g−1, which increased by 59% compare to that of RAC. These results are attributed to multiple factors of the negative surface charge and the OCP formed by C F bonds, which diminish the co-ion expulsion effect, thereby enhancing the CDI performance. Graphical abstract Unlabelled Image Highlights • C-F bonds are introduced on the Activated Carbon(AC) surface by fluorination, resulting in a negative surface charge. • Fluorinated Activated Carbon(FAC) is used as a cathode in a CDI cell. • The electrosorption capacity and charge efficiency of the FAC are improved by the negative charge formed on the AC surface and by the higher OCP of the CDI cell. • FAC can effectively attract cations and reduce the co-ion expulsion effect. [ABSTRACT FROM AUTHOR]

Activated carbons (ACs) were fluorinated and fabricated into electrodes to investigate the effect of fluorination on asymmetric capacitive deionization (CDI). Fluorine functional groups were introduced on the AC surfaces via fluorination. The specific capacitance of the fluorinated AC (F AC) electrode increased drastically from 261 to 337 F/g compared with the untreated AC (R AC) electrode at a scan rate of 5 mV/s, despite a decrease in the specific surface area and total pore volume after fluorination. The desalination behavior of asymmetric CDI cells assembled with an R AC electrode as the counter electrode and an F AC electrode as the cathode (R || F-) or anode (R || F + ) was studied. For R || F-, the salt adsorption capacity and charge efficiency increased from 10.6 mg/g and 0.58–12.4 mg/g and 0.75, respectively, compared with the CDI cell assembled with identical R AC electrodes at 1 V. This CDI cell exhibited consistently better salt adsorption capacity and charge efficiency at different applied voltages because F AC electrodes have a cation attractive effect originating from the partially negatively charged fluorine functional groups on the AC surface. Therefore, co-ion expulsion in the F AC electrode as the cathode is effectively diminished, leading to enhanced CDI performance. [ABSTRACT FROM AUTHOR]

The mechanisms of the SO 2 adsorption properties of activated carbon fibers (ACFs) after plasma treatment were studied. The surfaces of the ACFs were modified by a plasma treatment using N 2 gas to enhance the SO 2 adsorption of the fibers based on the effects of introduced nitrogen functional groups, especially quaternary nitrogen groups. Through the comparative analysis of X-ray photoelectron spectroscopy (XPS), especially the N1s component and SO 2 adsorption data, quaternary nitrogen groups were determined to be effectively introduced onto the surface of the ACFs. SO 2 molecules have lone pair electrons and attach themselves to the ACFs’ pores as the concentration of quaternary nitrogen increases. However, the pyridine N-oxide (N-X) functional group exhibited acidic properties and had a neutralizing effect on the ACF surfaces, reducing the strength of electrostatic interactions with the SO 2 molecules. These types of mechanisms are proved by various physicochemical and electrical characterizations, especially the SO 2 sensing capability of plasma-treated ACFs. The reversible sensing indicates that N 2 plasma treatment changed the electrical properties of the carbon sample, leading to an intriguing sensing mechanism. [ABSTRACT FROM AUTHOR]

Activated carbon fibers (ACFs) with controlled pore sizes were prepared by KOH activation to efficiently capture CO 2 molecules. The surfaces of the ACFs were modified by liquid oxidation using hydrofluoric acid to enhance the adsorption of CO 2 by the fibers based on the effects of the oxygen-containing functional groups introduced on the surface. Oxygen-containing functional groups were effectively introduced onto the surfaces of the ACFs based on the fluorine radical effect, and they attached themselves to the pores of the ACFs as the concentration of hydrofluoric acid increased. The oxygen-containing functional groups, such as carboxylic and hydroxyl groups, on the surfaces of the ACFs played an important role in guiding CO 2 into the micropores via the attractive forces experienced by the electrons in the CO 2 molecules. [ABSTRACT FROM AUTHOR]

Highlights: [•] Nitrogen doping of activated carbon fibers (ACFs) by urea treatment could be enhanced the electrical conductivity and interaction with biomaterials. [•] Hydrophilic and mesoporous carbon fibers were prepared through activation process using KOH as activation agent. [•] Mesopore structures were more helpful for immobilization of enzymes than microporous carbon materials. [•] The glucose sensitivity of the N-doped ACFs was higher than untreated ACF sample. [ABSTRACT FROM AUTHOR]

Abstract: To improve the electrochemical performance of an activated carbon (AC)-based electric double-layer capacitor (EDLC), the AC surface, which is used as an electrode, was modified using different concentrations of phosphoric acid. The effects of the treatment on the surface and electrochemical properties of the AC electrodes were investigated. The specific capacitance increased from 256F/g for an untreated sample to 452F/g for a sample treated with a 2M solution at a scan rate of 5mV/s. This increase can be attributed to an increase in the mesopore volume caused by the etching effect of the reaction between the carbon surfaces and phosphoric acid. In addition, oxygen functional groups, which were introduced by the treatment, improved the electrochemical properties of the resulting AC-based electrode. Therefore, simultaneous etching and oxygen introduction with phosphoric acid can easily bind oxygen functional groups (particularly Che surface of an AC electrode. This method is effective at preparing AC for use in an EDLC with improved electrochemical properties. [Copyright &y& Elsevier]

Abstract: The surface of phenol-based activated carbon (AC) was seriatim amino-fluorinated with solution of ammonium hydroxide and hydrofluoric acid in varying ratio to fabricate electrode materials for use in an electric double-layer capacitor (EDLC). The specific capacitance of the amino-fluorinated AC-based EDLC was measured in a 1M H2SO4 electrolyte, in which it was observed that the specific capacitances increased from 215 to 389Fg−1 and 119 and 250Fg−1 with the current densities of 0.1 and 1.0Ag−1, respectively, in comparison with those of an untreated AC-based EDLC when the amino-fluorination was optimized via seriatim mixed solution of 7.43molL−1 ammonium hydroxide and 2.06molL−1 hydrofluoric acid. This enhancement of capacitance was attributed to the synergistic effects of an increased electrochemical activity due to the formation of surface N- and F-functional groups and increased, specific surface area, and mesopore volumes, all of which resulted from the amino-fluorination of the electrode material. [Copyright &y& Elsevier]

Abstract: Activated multi-walled carbon nanotubes were prepared with appended vanadium as a hydrogen storage medium. The pore structure was significantly improved by an activation process that was studied using Raman spectroscopy, field emission transmission electron microscopy and pore analysis techniques. X-ray photoelectron spectroscopy and X-ray diffraction results reveal that the vanadium catalyst was introduced into the carbon nanotubes in controlled proportions, forming V8C7. The improved pore structure functioned as a path through the carbon nanotubes that encouraged hydrogen molecule adsorption, and the introduced vanadium catalyst led to high levels of hydrogen storage through the dissociation of hydrogen molecules via the spill-over phenomenon. The hydrogen storage behavior was investigated by electrical resistance measurements for the hydrogen adsorbed on a prepared sample. The proposed mechanism of hydrogen storage suggests that the vanadium catalyst increases not only the amount of hydrogen that is stored but also the speed at which it is stored. A hydrogen storage capacity of 2.26wt.% was achieved with the activation effects and the vanadium catalyst at 30°C and 10MPa. [Copyright &y& Elsevier]

Abstract: The surface of phenol-based activated carbon (AC) was fluorinated at room temperature with different F2:N2 gas mixtures for use as an electrode material in an electric double-layer capacitor (EDLC). The effect of surface fluorination on EDLC electrochemical performance was investigated. The specific capacitance of the fluorinated AC-based EDLC was measured in a 1M H2SO4 electrolyte, in which it was observed that the specific capacitances increased from 375 and 145Fg−1 to 491 and 212Fg−1 with the scan rates of 2 and 50mVs−1, respectively, in comparison to those of an unfluorinated AC-based EDLC when the fluorination process was optimized via 0.2bar partial F2 gas pressure. This enhancement in capacitance can be attributed to the synergistic effect of increased polarization on the AC surface, specific surface area, and micro and mesopore volumes, all of which were induced by the fluorination process. The observed increase in polarization was derived from a highly electronegative fluorine functional group that emerged due to the fluorination process. The increased surface area and pore volume of the AC was derived from the physical function of the fluorine functional group. [Copyright &y& Elsevier]

Abstract: A glucose sensor electrode was prepared from electrospun spherical-type carbon materials. The glucose oxidase (GOD) enzyme was immobilized on a prepared electrode for efficient glucose sensing. The GOD immobilization was maximized by enlarged sites of carbon electrode and improved interfacial affinity between the carbon surface and the GOD achieved via physical activation and oxyfluorination, respectively. The specific surface area was enlarged significantly, by over 42 fold, through physical activation. In addition, the hydrophobic carbon surface was modified with hydrophilic functional groups by direct oxyfluorination for improved interfacial affinity between the carbon and GOD. Accordingly, the GOD immobilization improved significantly by approximately 9 fold. The glucose sensor was evaluated by amperometric measurements and cyclic voltammetry. The measured current increased with higher glucose concentrations based on the effects of the developed pore structure and the introduced hydrophilic functional groups. The enzymatic kinetics were also studied using the Lineweaver–Burk equation. The sensitivity of the glucose sensor was improved by approximately 3 fold with increased maximum current, whereas the GOD enzyme activity was diminished by efficient GOD immobilization. Conclusively, a high-performance glucose sensor was obtained using an electrospun spherical-type carbon material due to efficient GOD enzyme immobilization. [Copyright &y& Elsevier]

Abstract: The surface of a phenol-based activated carbons (ACs) used as an electrode in an electric double-layer capacitor (EDLC) was oxyfluorinated at room temperature with different F2:O2 gas mixtures, and the effects of these surface modifications on EDLC electrical performance were investigated. The specific capacitance of the oxyfluorinated AC-based EDLC was measured in a 1M H2SO4 electrolyte, in which it was observed that the specific capacitances increased from 375 and 145Fg−1 to 391 and 189Fg−1 with the scan rates of 5 and 50mVs−1, respectively, over compared to those of an untreated AC-based EDLC when the oxyfluorination ratio was at the optimal F2:O2 =5:5. This was attributed to the synergistic effect of surface chemical compositions and textural properties of the resulting oxyfluorinated AC, which had the highest micropore volume, an optimal mesopore volume, and electrochemically active surface functional groups, such as C–F and quinone Cmple-para> [Copyright &y& Elsevier]

Abstract: This study introduces amino-fluorination, a novel chemical modification method for activated carbon (AC), and investigates the surface and electrochemical properties of the resulting AC. The procedure was modified by controlling the surface reaction with concentrated ammonium hydroxide and diluted hydrofluoric acid or diluted ammonium hydroxide and concentrated hydrofluoric acid. Amino-fluorination of AC with concentrated ammonium hydroxide and diluted hydrofluoric acid significantly increased the specific surface area, total pore volume, mesopore volume, and number of N- and F-containing surface functional groups and decreased the number of O-containing surface functional groups. These changes resulted in improving the specific capacity to 417F/g at a scan rate of 10mVs−1 from the specific capacity of raw AC-based EDLCs (241F/g). On the other hand, amino-fluorination of AC with diluted ammonium hydroxide and concentrated hydrofluoric acid increased the specific surface area, total pore volume, mesopore volume, and number of N-, O-, and F-containing surface functional groups. These changes resulted in the highest specific capacitance for the prepared AC-based EDLCs (485F/g), with a 101% increase compared to the raw-AC-based EDLCs. Therefore, the amino-fluorination of AC is a simple and efficient way to enhance the performance of AC-based EDLCs. [Copyright &y& Elsevier]

Abstract: Nano-sized carbon fibers were prepared by using electrospinning, and their electrochemical properties were investigated as a possible electrode material for use as an electric double-layer capacitor (EDLC). To improve the electrode capacitance of EDLC, we implemented a three-step optimization. First, metal catalyst was introduced into the carbon fibers due to the excellent conductivity of metal. Vanadium pentoxide was used because it could be converted to vanadium for improved conductivity as the pore structure develops during the carbonization step. Vanadium catalyst was well dispersed in the carbon fibers, improving the capacitance of the electrode. Second, pore-size development was manipulated to obtain small mesopore sizes ranging from 2 to 5 nm. Through chemical activation, carbon fibers with controlled pore sizes were prepared with a high specific surface and pore volume, and their pore structure was investigated by using a BET apparatus. Finally, polyacrylonitrile was used as a carbon precursor to enrich for nitrogen content in the final product because nitrogen is known to improve electrode capacitance. Ultimately, the electrospun activated carbon fibers containing vanadium show improved functionality in charge/discharge, cyclic voltammetry, and specific capacitance compared with other samples because of an optimal combination of vanadium, nitrogen, and fixed pore structures. [Copyright &y& Elsevier]

Abstract: Spherical activated carbon (AC) containing photocatalyst was prepared using strong and weak acid ion-exchange resins as starting materials. These resins were treated with an aqueous solution of Zn2+ or and both treated resins and non-treated resins were carbonized and activated. The physicochemical characteristics of the AC samples were examined using XRD, SEM, EDS, BET, EPMA, ESR, compressive strength and zinc content. The photocatalytic activity was evaluated by measuring the humic acid (HA) removal efficiency using UV/photocatalyst system. When strong acid ion-exchange resins (SZ samples) were used to prepare AC containing zinc, the zinc was found to have ZnS crystal structures, whereas in case of the use of weak acid ion-exchange resins (WZ samples), the zinc was found to have ZnO crystal structure. Both the SZ and WZ samples had spherical shape except the WZ-A-900 and had a good BET specific surface area. In the HA removal test using a floating UV/photocatalyst system, the WZ samples showed higher HA removal efficiency than the SZ samples. [Copyright &y& Elsevier]