High Surface Area Activated Carbon Research Articles

Revealing the causes of degradation of an asymmetric ionic liquid supercapacitor with a composite polyaniline/carbon electrode

The extended window of electrochemical stability of ionic liquids and the high specific capacitance values of activated carbon (AC)/conductive polymer (polyaniline, Pani) composite materials are promising approaches to improve the performance of supercapacitors (SC).In this work, we studied the stability of an asymmetric AC//Pani-C cell with 1 M solution of 1-butyl-3-methylimidazolium tetrafluoroborate (BMIMBF4) in acetonitrile as an electrolyte. Pani-C (56 wt% of Pani) composite was prepared by oxidative polymerization of aniline in the presence of high surface area AC (SBET = 2300 m2‧g−1). Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, transmission and scanning electron microscopies data confirmed the formation of Pani-C composite. Combination of cyclic voltammetry, galvanostatic charge/discharge method, and electrochemical impedance spectroscopy in 2- and 3-electrode cell configurations gave information about anodic (1 V vs. Ti) and cathodic (−1.8 V vs. Ti) potential limits of electrochemical stability, and potential of zero charge of Pani-C and AC.From these data, optimal mass ratio of Pani-C and AC electrodes was obtained for asymmetric SC assembly. It was found that after 500 charge/discharge cycles, the capacitance of the asymmetric AC//Pani-C SC decreased by 15% from 46.8 to 39.9 F·g−1 as a result of Pani-C degradation. The specific capacitance of AC remained virtually unchanged (decreased from 144 to 141 F·g−1), while that of Pani-C decreased by 8.7% from 230 to 210 F·g−1. Electrochemical measurements showed that degradation is accompanied by an increase in the working potential window of Pani-C (from 0.85 V to 0.97 V) and a shift in Emin…Emax working potentials from 0.15 … 1 to 0.52 … 1.49 V vs. Ti in the beginning and in the end of stability test, respectively. The last region is related to the potential for non-conductive pernigraniline formation (1.3 V vs. Ti). It was shown that the main reason of AC//Pani-C SC capacitance decay is a gradual increase in the operating potential window with a constantly shifts towards anodic values of positive Pani-C electrode, which resulted in accumulation of nonconductive polymer form that does not participate in charge accumulation.

Optimization of cationic dye removal using a high surface area-activated carbon from water treatment sludge

A high surface area-activated carbon from water treatment sludge (WTS) was employed as adsorbent material to remove methylene blue (MB) dye from aqueous solutions. In this research, the effect of parameters of adsorbent dosage, time of contact, and pH on adsorption capacity and efficiency were determined. Global desirability methodology was applied by using central composite rotational statistical design in order to optimize the adsorption of dye solution of MB by washed activated sludge carbon (WASC). Activated carbons obtained from WTS were characterized by FTIR, TGA, XRD and BET techniques. The mesoporous material WASC showed a total pore volume of 0.439 cm3 g−1 and the largest specific surface area of 582.0 m2 g−1. The production of WASC indicates to be an excellent option in the sustainable use of WTS residue.

Temperature dependence for high electrical performance of Mn-doped high surface area activated carbon (HSAC) as additives for hybrid capacitor

Herein, we manufactured the positive and negative electrodes for the hybrid capacitor. The Mn-doped High surface area of Activated carbon composite used for the positive electrode and as-prepared composite was calcined at 600 °C and 800 °C. The morphological structures and pore-size distributions of MnYP-600HTT and MnYP-800HTT were characterized by means of XRD, SEM, EDAX, TEM, and BET. According to the BET specific surface-area evaluation, MnYP-600HTT and MnYP-800HTT were 1272.6 and 1388.1 m2/g, respectively. Total pore volumes were 0.627 and 0.687 cm3/g, which is beneficial for forming ion-transport channels in electrochemical reactions. The MnYP-600HTT electrode had a high specific capacity of 177.2 mAh/g at 20C, and the capacity retention was 64.8%. During the entire cycling, MnYP-600HTT had excellent cyclic stability in 500 cycles along with high efficiency. The robust design of the MnYP-600HTT and MnYP-800HTT cathode materials introduced in this work pave the way for designing next-generation supercapacitors operating at ultra-high C rates. The Mn-doped high surface of activated carbon had stable energy density and superior cycling stability that were demonstrated in supercapacitor systems.

Synthesis of a Very High Specific Surface Area Active Carbon and Its Electrical Double-Layer Capacitor Properties in Organic Electrolytes

A new porous activated carbon (AC) material with very high specific surface area (3193 m2 g−1) was prepared by the carbonization of a colloidal silica-templated melamine–formaldehyde (MF) polymer composite followed by KOH-activation. Several electrical double-layer capacitor (EDLC) cells were fabricated using this AC as the electrode material. A number of organic solvent-based electrolyte formulations were examined to optimize the EDLC performance. Both high specific discharge capacitance of 130.5 F g−1 and energy density 47.9 Wh kg−1 were achieved for the initial cycling. The long-term cycling performance was also measured.

Production and characterisation of activated carbon and carbon nanotubes from potato peel waste and their application in heavy metal removal.

Herein, activated carbon (AC) and carbon nanotubes (CNTs) were synthesised from potato peel waste (PPW). Different ACs were synthesised via two activation steps: firstly, with phosphoric acid (designated PP) and then using potassium hydroxide (designated PK). The AC produced after the two activation steps showed a surface area as high as 833 m2 g−1 with a pore volume of 0.44 cm3 g−1, where the raw material of PPW showed a surface area < 4 m2 g−1. This can help aid and facilitate the concept of the circular economy by effectively up-cycling and valorising waste lignocellulosic biomass such as potato peel waste to high surface area AC and subsequently, multi-walled carbon nanotubes (MWCNTs). Consequently, MWCNTs were prepared from the produced AC by mixing it with the nitrogen-based material melamine and iron precursor, iron (III) oxalate hexahydrate. This produced hydrophilic multi-wall carbon nanotubes (MWCNTs) with a water contact angle of θ = 14.97 °. Both AC and CNT materials were used in heavy metal removal (HMR) where the maximum lead absorption was observed for sample PK with a 84% removal capacity after the first hour of testing. This result signifies that the synthesis of these up-cycled materials can have applications in areas such as wastewater treatment or other conventional AC/CNT end uses with a rapid cycle time in a two-fold approach to improve the eco-friendly synthesis of such value-added products and the circular economy from a significant waste stream, i.e., PPW.Graphical abstract.

Upcycling brewer's spent grain waste into activated carbon and carbon nanotubes for energy and other applications via two‐stage activation

AbstractBACKGROUNDBrewer's Spent Grain (BSG), a form of lignocellulosic biomass more commonly known as barley waste was used to synthesize activated carbon (AC) and carbon nanotubes (CNTs). The produced materials were used in water remediation application.RESULTSA novel approach involving two activation steps; first, with phosphoric acid (designated BAC‐P) and then using potassium hydroxide (designated BAC‐K) was proposed for the production of AC and CNTs from BSG. The AC produced showed a surface area as high as 692.3 m2 g−1 with a pore volume of 0.44 cm3 g−1. This can help aid and facilitate the circular economy by effectively upcycling and valorizing waste lignocellulosic biomass to high surface area AC and subsequently, multi‐walled carbon nanotubes (MWCNTs). Consequently, MWCNTs were prepared from the produced AC by mixing it with the nitrogen (N)‐based material melamine and iron precursor, iron (III) oxalate hexahydrate, where it produced hydrophilic MWCNTs. Both AC and CNT materials were used in heavy metal removal (HMR), where the maximum lead absorption was observed for sample BAC‐K with 77% removal capacity after the first hour of testing.CONCLUSIONThis result signifies that the synthesis of these upcycled materials can have an application in the areas of wastewater treatment or other AC/CNT end uses with a rapid cycle time. © 2019 Society of Chemical Industry

A Pongamia pinnata pods based activated carbon as an efficient scavenger for adsorption of toxic Co(II): kinetic and thermodynamic study

ABSTRACT A porous and high surface area-activated carbon based on Pongamia pinnata pods (PPP) was synthesized using a chemical method. The synthesized material was characterized using FTIR, XRD, BET, SEM, EDX, XPS and TGA. Plausible adsorption mechanism of Co(II) on PPPAC was evaluated systematically. The effect of various contributing parameters were investigated through batch adsorption experiments. Results reveal that the equilibrium was attained within 360 min having 0.35 g PPPAC amount at pH 6 and the maximum equilibrium capacity was observed 190.30 mg/g. Kinetically adsorption of Co(II) was best described by pseudo-second-order-model. The equilibrium data well suited with the Langmuir isotherm model and thermodynamic parameters indicate that the process was spontaneous and endothermic in nature.

Removal of Basic Dye from Aqueous Medium Using Activated Carbon from Erythrina Brucei, Arundinaria Alpina and Manihot Esculenta

This work deals with the preparation of activated carbon (AC) from Korch ( Erythrina brucei ) sawdust (EB), Bamboo ( Arundinaria alpina ) sawdust (AA), and Cassava peel ( Manihot esculenta ) powder (ME) to remove methylene blue (MB) from aqueous solution. The effect of temperature, chemical impregnation (H 3 PO 4 , ZnCl 2 , KOH and H 2 SO 4 ) were done. The optimum temperature used to prepare activated carbon of EB, AA and ME were700 , 400 and 600 respectively. High surface area AC was obtained by chemical activation of biomaterial with H 3 PO 4 . The effect of various process parameters like pH, contact time, adsorbent dose on the efficiency MB removal was investigated. The optimum pH value and contact time for AC of EB, AA and ME was determined as 6, 5, 4 and 40, 50, 60 min respectively. The optimum adsorbent dose of EB, AA and ME were determined 0.04, 0.06 and 0.12g respectively in 25ml of solution. Thermodynamic analysis asserted endothermic and spontaneous nature of the system. Equilibrium data were represented better by Langmuir model than Freundlich which describes monolayer adsorption. The linear regression analysis of kinetic data confirmed that Pseudo-second order rate expression. Keywords : activated carbon, E. brucei , A. alpina , M. esculenta , methylene blue. DOI : 10.7176/FSQM/86-03 Publication date : April 30 th 2019

Furfuryl alcohol derived high-end carbons for ultrafast dual carbon lithium ion capacitors

In this work, a lithium ion capacitor (LIC) based on carbon electrodes prepared from furfuryl alcohol-derived polymers is presented. While furfuryl alcohol is not a new carbon precursor, it has been evaluated in the past mainly for negative electrodes with Li-ion insertion. Here we describe both an activated carbon (AC) and a hard carbon (HC) made from the same furfuryl alcohol-derived polymers, for both electrodes of the LIC. The polymerization technique used to make carbon from the furfuryl alcohol precursor is different from all the methods described earlier, and is flexible enough to make soft, high surface area AC, as well as a denser, low surface area HC. The HC and the HC-based negative electrode used in this study are targeted at a high-energy and high-power LIC application by specifically reducing the carbon particle size to sub-micrometric levels, using a HC with a specific surface area of ∼300 m2 g−1 and keeping the electrode mass loading to <2 mg cm−2. The HC delivers a stable capacity of ∼400 mAh g−1vs. Li+/Li at C/10, with excellent capacity retention of 50% at 10C (>200 mAh g−1) and 25% at 50C (∼100 mAh g−1). The AC used for the capacitor-type positive electrode was activated to a specific surface area of ∼1670 m2 g−1. For comparison purposes, a symmetric electric double layer capacitor (EDLC) using the same AC, in a 1.5 M Et4NBF4 (acetonitrile) electrolyte, was also fabricated. Overall, the LIC showed considerably higher energy density over its EDLC counterpart, delivering a maximum energy density (based on the total electrode active mass weight) of 150 Wh kg−1AM at a power density of 150 W kg−1AM, with a 66% retention of the initial energy at the highly demanding 10,000 W kg−1AM power peak point. Additionally, long cycle life was measured, with 83% capacitance retention after 10,000 cycles.

Transfer-hydrogenation of furfural and levulinic acid over supported copper catalyst

Transfer-hydrogenation (TH) has attracted great attention because it does not require the use of high pressure H2. In this work, we report a facile ultrasound-assisted impregnation method with the aid of carbothermal reduction property of activated carbon (AC) to synthesize AC supported copper catalyst (Cu/AC) for efficient TH of bio-derived unsaturated oxygenated compounds such as furfural (FAL) and levulinic acid (LA). In the presence of 2-propanol as the hydrogen donor, within 5 h under 200 °C, the resultant Cu/AC catalyst can convert FAL into 2-methylfuran (2-MF, a high-value fuel additive) with a superior selectivity of 91.6%. The Cu/AC catalyst can also covert LA into γ-valerolactone (GVL) with a high selectivity of 89.9% under 220 °C for 5 h. The superior TH catalytic performance of the Cu/AC catalyst could be attributed to the uniform size and well dispersed Cu nanoparticles supported on the high surface area AC with the suitable proportion of Cu2+, Cu0 and Cu+. Cycling test results confirm the reusability of the Cu/AC catalyst. Additionally, the reported Cu/AC catalyst is cheap and massive producible, advantageous for large-scale conversion of bio-derived platforms to value-added chemicals and bio-fuels.

Preparation of High Surface Area Activated Carbon from Spent Phenolic Resin by Microwave Heating and KOH Activation

AbstractThe spent phenolic resin is as raw material for preparing high surface area activated carbon (HSAAC) by microwave-assisted KOH activation. The effects of microwave power, activation duration and impregnation ratio (IR) on the iodine adsorption capability and yield of HSAAC were investigated. The surface characteristics of HSAAC were characterized by nitrogen adsorption isotherms, FTIR, SEM and TEM. The operating variables were optimized utilizing the response surface methodology (RSM) and were identified to be microwave power of 700 W, activation duration of 15 min and IR of 4, corresponding to a yield of 51.25 % and an iodine number of 2,384 mg/g. The pore structure parameters of the HSAAC, i. e., Brunauer–Emmett–Teller (BET) surface area, total pore volume, and average pore diameter were estimated to be 4,269 m2/g, 2.396 ml/g and 2.25 nm, respectively, under optimum conditions. The findings strongly support the feasibility of microwave-assisted KOH activation for preparation of HSAAC from spent phenolic resin.

Production of high surface area-activated carbons from waste bamboo scaffolding

Bamboo, indigenous to Hong Kong and China, is widely used as scaffolding in construction and building projects. Over 50,000 tonnes of bamboo scaffolding waste is disposed as landfill waste each yea...

A Study of Mediators As Ion Providers in Supercapactors

Doping mediators (soluble redox compounds) in polymer electrolyte contained in the porous electrodes is an effective method to increase the capacitance of supercapacitors. Mediators not only provide additional capacitance but also ions to electrolyte. The total capacity of a supercapacitor is dominated by the minor of the electrode capacity and the number of ions in electrolyte. In this research, we focused on revealing the effect of on the extra ions provided by the mediators during the charge/discharge processes. Two types of supercapacitors were fabricated. For the first type, the active electrode material consisted of 50 wt% mediators (in solid state) and 50 wt% high specific surface area active carbon (AC). For the other type of supercapacitor, the active electrode material consisted of AC only. Acetonitrile was used as liquid phase for both types. Under this circumstance, ions are provided by mediator only. The calculation of specific current was based on total weight of two electrodes and cyclic voltammetry (CV) curves. As shown in Figure 1, supercapacitor (a) (AC only) is unable to store any charges and energy without the ions in the solution. However, supercapacitor (b) can store ten times more energy with the mediator enhancement. In this situation, we can consider mediators as ‘charge harbor’. They can release ions into the liquid phase. These ions then participate in formation of electric double layers (EDLs) on AC. This capability of providing ions into the liquid phase can increase capacity of supercapacitor. CVs (b) and (c) also indicate that different mediators are different in the kinetics of providing ions. Taking supercapacitor (b) as an example, when we charge the supercapacitor, the K2CuFe(CN)6 can release K+ cation into the liquid phase and [CuFe(CN)6]- will still be hold on the solid phase because of the electrostatic force. On the other hand, we can use VOSO4 as a mediator too. V4+ can be reduced and releases SO4 2- anion. Thus, it is preferred to use K2CuFe(CN)6 in the positive electrode while use VOSO4 in the negative electrode. An series of mediators were evaluated using the same method. Figure 1

Effect of Metal Complex Mediators on the Performance of Mediator Supercapacitor

Demand of electrical energy storages is increasing quickly with market expansion of cell phones, electrical vehicles, and stationary energy storage. Supercapacitor is an alternative choice of rechargeable batteries because of their low cost for fabrication and maintenance, high cycle life, high charge rate, and high specific power. Using mediators to enhance the performance of the carbon materials based supercapacitors is more effective than using conductive polymer or metal oxide materials. In this study, we improved the performance using metal complex mediators. Several different mediators were synthesized and compared in this work. The active electrode material consisted of 10% mediator, 90% high specific surface area active carbon (AC). An EDLC made by AC only was also fabricated as a reference. To qualify the industrial requirements, current collector, electrolyte and separator are all commercial. The prototypes were fabricated in the glove box and sealed under vacuum. The calculation of specific energy (SE) was based on total mass of both electrodes and cyclic voltammetry (CV) curves and glvanostatic charge/discharge curves (GCDs). Typical CVs were shown in Figure 1. The mediator supercapacitor exhibited high energy densities (˃40 Wh kg-1), high charge/discharge efficiency (˃99%) and high reversibility (˃90% after 10000 cycles). The effect of the rare earth and transition metals on the effectiveness of the mediators is investigated. As shown in Table 1, for mediators containing rare earth metals, Pr, La, Y are more effective than Ho. For mediators containing transition metals, Mn, Fe, and Co are more effective than Zn. The authors explain the phenomenon with the notions of molecular configurations, electronic structures, and interactions between charged mediators. Figure 1

Effect of elemental sulfur in precursors on the pore structure and surface chemical characteristics of high-surface area activated carbon

Analog sulfur-containing precursors (ASCPs) have been prepared by adding a certain amount of elemental sulfur (ES) into petroleum coke (PC) for synthesis of high-surface area activated carbon (HAC). ASCPs make it feasible to control the speciation and content of sulfur in ASCPs, so as to accurately investigate the influence of ES on the pore structure and surface chemical characteristics of the resultant HAC. The results indicate that ES in ASCPs can react with activator KOH and consume a part of KOH amount, thus leading to the deficiency of actual KOH amount for PC activation, eventually making a decrease in the specific surface area and pore volume of HAC. Interestingly, some of ES in ASCPs is transformed into organic sulfur thioether (C–S–C) and sulfate (C–SO4–C) or sulfonate (C–SO3–C) on HAC surface during the activation process. Therefore, the surface chemical characteristics of HAC are modified correspondingly.

More sustainable energy storage: lignin based electrodes with glyoxal crosslinking

Crosslinking lignin on high surface area active carbon using glyoxal as a green crosslinker leads to truly sustainable electrodes with improved performance.

Porous high specific surface area-activated carbon with co-doping N, S and P for high-performance supercapacitors

Porous high specific surface area activated carbon with co-doping N, S and P for high-performance supercapacitors.

Carbon electrode materials for supercapacitors obtained by co-carbonization of coal-tar pitch and sawdust

High-surface area-activated carbons (ACs) are successfully prepared by coal-tar pitch (CTP)/sawdust (SD) co-carbonization followed by simple KOH activation. The ACs inherit the tubular morphology of the biomass and possess a hierarchical porous structure, a high specific surface area of 2224 m2/g, and a considerable amount of oxygen-containing species on the surface. The AC obtained from the co-carbonization of 67 % CTP and 33 % SD has a 25 wt% higher oxygen content than the AC (0.17 wt%) from 100 % CTP, and has a 27.50 wt% higher carbon yield than the AC (14.42 wt%) from SD. As an electrode material for supercapacitors, the prepared electrode from 67 % CTP and 33 % SD exhibits a favorable specific capacitance of 251 F/g at a current density of 0.5 A/g in 6 mol/L KOH electrolyte. The electrode also demonstrates excellent cycling stability with a retention rate of 93 % over 7000 cycles at 2 A/g and a favorable rate capability with a retention rate of 74 % when the current density increases from 0.5 to 5 A/g. Therefore, the ACs obtained by co-carbonizing CTP and SD have high potential as electrode materials. This route not only enhances the benefit from agricultural wastes, but also reduces the cost of producing electrode materials for supercapacitors.

Effects of Temperature and Pore Structure on High Surface Area-Activated Carbon Obtained from Peanut Shells

Activated carbon was synthesized from peanut shells by treating with H3PO4 with an intention to enhance the surface area and to find its electrochemical performance in EDLC as electrode material. The powdered peanut shells were pyrolyzed at three different temperatures namely 300 degrees C, 600 degrees C and 800 degrees C respectively. The structural and surface properties of the pyrolyzed carbon materials were studied using N2 adsorption/desorption, Raman, TEM and SEM analysis. There has been remarkable increase in the surface area of the carbon pyrolyzed at 600 degrees C due to the effect of pore generations. The surface area of the 600 degrees C pyrolyzed sample was found to be 1629 m2/g. The electrochemical properties of all the samples were evaluated by cyclic voltammetry, impedance spectroscopy, and galvanostatic charge-discharge tests. The system showed excellent cycleability and a maximum specific capacitance of 291 Fg(-1) was obtained in a 0.1 M H2SO4 electrolyte solution. The effects of the various properties of the activated carbon on the EDLC performance are discussed.

Electrochemical performances of hydrothermal tannin-based carbons doped with nitrogen

Six porous carbon materials, produced by hydrothermal treatment of flavonoid tannin and subsequent carbonization at 1173K, were tested as electrodes of supercapacitors. Four of these carbons were doped with nitrogen by putting tannin in contact with ammonia before or during the hydrothermal treatment. The pyrolyzed hydrothermal carbons had moderate surface areas, within the range 442–684m2g−1, and nitrogen contents ranging from 0.7 to 8.0wt.%. Specific capacitances as high as 320Fg−1 and normalized capacitances as high as 58μFcm−2 were measured at 2mVs−1. These performances are comparable with those obtained with high surface area-activated carbons, whereas, normalized capacitances values are among the highest ever reported. Mesostructuration, within the range 3–13nm, of these materials appears to be a good strategy to improve their electrochemical performances at higher scan rates. We confirmed the beneficial role of oxygen up to 18wt.%, while an optimum in nitrogen content exists from 3 to 6wt.%.