Rational synthesis of graphitic porous carbon with high content nitrogen doping via ultra-fast pyrolysis of ZIF-8 for electrochemical capacitor with enhanced performance

2019 ◽  
Vol 12 (06) ◽  
pp. 1951004
Author(s):  
Tie Gao ◽  
Haibo Li
Keyword(s):  
Specific Surface ◽  
Specific Capacitance ◽  
Surface Area ◽  
Specific Surface Area ◽  
Rate Capability ◽  
Total Pore Volume ◽  
High Specific Capacitance ◽  
Superior Performance ◽  
Large Specific Surface Area ◽  
Average Pore

In this work, we proposed an effective strategy to prepare nitrogen-doped popcorn-like porous carbons (NPPCs) via ultra-fast carbonization of zeolitic immidazolate frameworks (ZIFs-8), where the ZIFs-8 acted as carbon precursor as well as the template. The obtained NPPCs possess popcorn-like morphology with large specific surface area of 1243[Formula: see text]m2/g, total pore volume of 1.48[Formula: see text]cm3/g and high nitrogen content. Remarkably, the average pore diameter of NPPCs was 4.72[Formula: see text]nm, indicating the presence of amount substantial mesopores. As the electrode of supercapacitor, the NPPCs revealed a relatively high specific capacitance of 610.4[Formula: see text]F/g in KOH (6[Formula: see text]mol/L) at 5[Formula: see text]mV/s. Even the scan rate was increased to 50[Formula: see text]mV/s, an impressive capacity of 424.8[Formula: see text]F/g can be achieved, suggesting good rate capability. Besides, it exhibited outstanding cycling stability with 93% of specific capacitance retention after 10,000 GCD cycles. Moreover, the NPPCs electrode demonstrated high electrochemical performance and stability by designing the coin-type and flexible supercapacitor. The large specific surface area, abundant accessible mesoporosity and novel nanostructure are account for the superior performance.

Facile synthesis of highly porous N-doped CNTs/Fe3C and its electrochemical properties

RSC Advances ◽  
2016 ◽  
Vol 6 (50) ◽  
pp. 44013-44018 ◽  
Author(s):  
Yanzhong Wang ◽  
Guoxiang Zhang ◽  
Guiwu Liu ◽  
Wei Liu ◽  
Huiyu Chen ◽  
...  
Keyword(s):  
Specific Surface ◽  
Electrochemical Properties ◽  
Specific Capacitance ◽  
Surface Area ◽  
Specific Surface Area ◽  
High Specific Capacitance ◽  
Large Specific Surface Area ◽  
Facile Synthesis ◽  
Highly Porous

Porous N-doped CNTs/Fe3C was synthesized by a facile method. N-doped CNTs/Fe3C possesses the large specific surface area up to 1021.26 m2g−1. It exhibits a high specific capacitance of 181 F g−1at 0.1 A g−1and excellent capacitance rate.

Modified polyacrylonitrile-based activated carbon fibers applied in supercapacitor

2016 ◽  
Vol 45 (3) ◽  
pp. 164-171 ◽  
Author(s):  
Linjie Su ◽  
Bohong Li ◽  
Dongyu Zhao ◽  
Chuanli Qin ◽  
Zheng Jin
Keyword(s):  
Activated Carbon ◽  
Specific Surface ◽  
Specific Capacitance ◽  
Surface Area ◽  
Specific Surface Area ◽  
Carbon Fibers ◽  
Electrode Material ◽  
High Specific Capacitance ◽  
Activated Carbon Fibers ◽  
Content Type

Purpose The purpose of this paper is to prepare a new modified activated carbon fibers (ACFs) of high specific capacitance used for electrode material of supercapacitor. Design/methodology/approach In this study, the specific capacitance of ACF was significantly increased by using the phenolic resin microspheres and melamine as modifiers to prepare modified PAN-based activated carbon fibers (MACFs) via electrospinning, pre-oxidation and carbonization. The symmetrical supercapacitor (using MACF as electrode) and hybrid supercapacitor (using MACF and activated carbon as electrodes) were tested in term of electrochemical properties by cyclic voltammetry, AC impedance and cycle stability test. Findings It was found that the specific capacitance value of the modified fibers were increased to 167 Fg-1 by adding modifiers (i.e. 20 wt.% microspheres and 15 wt.% melamine) compared to that of unmodified fibers (86.17 Fg-1). Specific capacitance of modified electrode material had little degradation over 10,000 cycles. This result can be attributed to that the modifiers embedded into the fibers changed the original morphology and enhanced the specific surface area of the fibers. Originality/value The modified ACFs in our study had high specific surface area and significantly high specific capacitance, which can be applied as efficient and environmental absorbent, and advanced electrode material of supercapacitor.

Preparation of Activated Carbons from Lignite for Electrochemical Capacitors by Microwave and Electrical Furnace Heating

2011 ◽  
Vol 194-196 ◽  
pp. 2472-2479 ◽  
Author(s):  
Bao Lin Xing ◽  
Chuan Xiang Zhang ◽  
Lun Jian Chen ◽  
Guang Xu Huang
Keyword(s):  
Specific Surface ◽  
Specific Capacitance ◽  
Surface Area ◽  
Specific Surface Area ◽  
Pore Volume ◽  
Activated Carbons ◽  
Electrochemical Capacitors ◽  
Weight Ratio ◽  
Total Pore Volume ◽  
Electrochemical Performances

Activated carbons (ACs) were prepared from lignite by microwave (MW) and electrical furnace (EF) heating with KOH as activation agent. In order to compare pore structures and electrochemical performances of ACs prepared by both heating methods, the ACs were characterized by N2 adsorption at 77K, X-ray diffraction (XRD) and scanning electron microscope (SEM). The electrochemical performances of Electrochemical capacitors (ECs) with ACs as electrodes in 3mol/L KOH electrolyte were evaluated by constant current charge-discharge, cyclic voltammetry and electrochemical impedance spectroscopy. The results show that the pore structures of ACs prepared by MW and EF heating significantly enhance when the weight ratio of KOH to coal increases from 2 to 4. The BET specific surface area, total pore volume, the ratio of mesopore and average pore diameter of ACs prepared by MW heating (denoted as AC-MW4) reaches 2094m2/g, 1.193cm3/g, 53.6%, 2.28nm when the weight ratio of KOH to coal is 4, and ACs prepared by EF heating (denoted as AC-EF4) reaches 2580m2/g, 1.683cm3/g, 67.3%, 2.61nm. The ECs with AC-MW4 and AC-EF4 as electrodes present a high specific capacitance of 348F/g and 377F/g at a current density of 50mA/g, and still remain 325F/g and 350F/g after 500 cycles, respectively. Although the specific surface area, total pore volume and specific capacitance of ACs prepared by MW heating are slightly lower than EF heating, taking into account the heating time in the activation process, ACs prepared by EF heating needs approximate 140min, while MW heating only needs 10min, which have demonstrated that microwave heating technology is a promising and efficient technique to prepare ACs.

scholarly journals PREPARATION OF MESOPOROUS TITANIA-SILICA AEROGELS BY CO2 SUPERCRITICAL EXTRACTION

2010 ◽  
Vol 7 (2) ◽  
pp. 121-127
Author(s):  
Silvester Tursiloadi ◽  
Dinie Mansur ◽  
Yeny Meliana ◽  
Ruslan Efendi
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Thermal Evolution ◽  
Anatase Phase ◽  
Sol Gel ◽  
Total Pore Volume ◽  
Acid Catalyst ◽  
Supercritical Extraction ◽  
Average Pore

Stable anatase is attractive because of its notable functions for photocatalysis and photon-electron transfer.  TiO2-nanoparticles dispersed SiO2 wet gels were prepared by hydrolysis of Ti(OC4H9n)4 and Si(OC2H5)4 in a 2-propanol solution with acid catalyst.  The solvent in the wet gels was supercritically extracted using CO2 at 60 oC and 22 Mpa in one-step.  Thermal evolution of the microstructure of the extracted gels (aerogels) was evaluated by XRD measurements, TEM and N2 adsorption measurements. The as-extracted aerogel with a large specific surface area, more than 365 m2g-1, contained anatase nanoparticles, about 5 nm in diameter.  The anatase phase was stable after calcinations at temperatures up to 1000 oC, and BET specific surface area, total pore volume and average pore diameter did not change significantly after calcinations at temperature up to 800 oC.   Keywords: Stable anatase, sol-gel, CO2 supercritical extraction.

Bead chain structure RFC/ACF by electrospinning for supercapacitors

2019 ◽  
Vol 48 (5) ◽  
pp. 439-448
Author(s):  
Lei Guo ◽  
Lien Zhu ◽  
Lei Ma ◽  
Jian Zhang ◽  
QiuYu Meng ◽  
...  
Keyword(s):  
Composite Material ◽  
Specific Surface ◽  
Specific Capacitance ◽  
Surface Area ◽  
Specific Surface Area ◽  
Carbon Fibers ◽  
High Specific Capacitance ◽  
Chain Structure ◽  
Cycle Stability ◽  
Content Type

Purpose The purpose of this paper is to prepare a spherical modifier-modified activated carbon fiber of high specific capacitance intended for electrode materials of supercapacitor. Design/methodology/approach In this study, phenolic-based microspheres are taken as modifiers to prepare PAN-based fiber composites by electrospinning, pre-oxidation and carbonization. Pearl-chain structures appear in RFC/ACF composites, and pure polyacrylonitrile fibers show a dense network. The shape and cross-linking degree are large. After the addition of the phenolic-based microspheres, the composite material exhibits a layered pearlite chain structure with a large porosity, and the RFC/ACF composite material is derived because of the existence of a large number of bead chain structures in the composite material. The density increases, the volume declines and the mass after being assembled into a supercapacitor as a positive electrode material decreases. The specific surface area of RFC/ACF composites is increased as compared to pure fibers. The increase in specific surface area could facilitate the diffusion of electrolyte ions in the material. Owing to the large number of bead chains, plenty of pore channels are provided for the diffusion of electrolyte ions, which is conducive to enhancing the electrochemical performance of the composite and improving the RFC/ACF composite and the specific capacitance of the material. The methods of electrochemical testing on symmetric supercapacitors (as positive electrodes) are three-electrode cyclic voltammetry, alternating current impedance and cycle stability. Findings The specific capacitance value of the composite material was found to be 389.2 F/g, and the specific capacitance of the electrode operating at a higher current density of 20 mA/cm2 was 11.87 F/g (the amount of the microsphere modifier added was 0.3 g). Using this material as a positive electrode to assemble into asymmetrical supercapacitor, after 2,000 cycles, the specific capacitance retention rate was 87.46 per cent, indicating excellent cycle stability performance. This result can be attributed to the fact that the modifier embedded in the fiber changes the porosity between the fibers, while improving the utilization of the carbon fibers and making it easier for electrolyte ions to enter the interior of the composites, thereby increasing the capacitance of the composites. Originality/value The modified PAN-based activated carbon fibers in the study had high specific surface area and significantly high specific capacitance, which makes it applicable as an efficient and environment-friendly absorbent, as well as an advanced electrode material for supercapacitor.

Optimization of Experimental Conditions for the Preparation of High Specific Surface Area Bamboo-Based Activated Carbon

2015 ◽  
Vol 1090 ◽  
pp. 154-159
Author(s):  
Sheng Zhou Zhang ◽  
Hong Ying Xia ◽  
Li Bo Zhang ◽  
Jin Hui Peng ◽  
Jian Wu ◽  
...  
Keyword(s):  
Activated Carbon ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Pore Volume ◽  
Total Pore Volume ◽  
High Specific Surface Area ◽  
Raw Material ◽  
Experimental Conditions ◽  
Average Pore

Bamboo as the raw material is carbonized to prepare high specific surface area activated carbon by microwave heating under nitrogen atmosphere in our present work. Influences of activation agents on the preparation of activated carbon are studied. The results show that activation agents have a significant influence on the preparation of activated carbon. Under the heating time of 15 min, the adsorption capacity of the activated carbon prepared utilizing KOH as activation agent is the best. When the KOH/C ratio is 4, the iodine number and yield of activated carbon are 2298 mg/g and 39.82%, respectively. The BET specific surface area, total pore volume and average pore diameter of activated carbon are 3441 m2/g, 2.093 ml/g and 2.434 nm, respectively. The micropore volume of 1.304 ml/g is 62.30% of total pore volume, indicating that the activated carbon is microporous activated carbon.

scholarly journals THE STABILIZING OF ANATASE AEROGEL AT HIGH TEMPERATURE

2010 ◽  
Vol 4 (2) ◽  
pp. 110-116 ◽  
Author(s):  
Silvester Tursiloadi ◽  
Hiroshi Hirashima
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Pore Volume ◽  
Anatase Phase ◽  
Total Pore Volume ◽  
Average Pore ◽  
Amorphous Sio2 ◽  
Bet Specific Surface Area ◽  
Sio2 Aerogel

Stable anatase is attractive to its notable functions for photo catalysis and photon-electron transfer.   Stable anatase TiO­2 containing amorphous SiO2 aerogel was prepared by hydrolysis of Ti (OC3H7)4 and Si (OC3H7)4 in a 2-propanol solution with acid catalyst. The solvent in wet gels was supercritically extracted in CO2 at 60 oC and 22 Mpa. Thermal evolutions of the microstructure of the gels were evaluated by TGA-DTA, N2 adsorption and XRD. A stable anatase TiO2 containing amorphous SiO2 aerogel with a BET specific surface area of 365 m2/g and a total pore volume of 0.20 cm3/g was obtained as prepared condition. The anatase phase was stable after calcination up to 1000 oC, and BET specific surface area, total pore volume and average pore diameter did not change significantly after calcination up to 900 oC.   Keywords: Supercritical extraction, sol-gel, aerogel, stable anatase structure

Architecture engineering of supercapacitor electrode materials

2016 ◽  
Vol 09 (01) ◽  
pp. 1640001 ◽  
Author(s):  
Kunfeng Chen ◽  
Gong Li ◽  
Dongfeng Xue
Keyword(s):  
Specific Surface ◽  
Specific Capacitance ◽  
Surface Area ◽  
Specific Surface Area ◽  
Electrode Materials ◽  
Electronic Conductivity ◽  
High Specific Capacitance ◽  
High Energy ◽  
Supercapacitor Electrode

The biggest challenge for today’s supercapacitor systems readily possessing high power density is their low energy density. Their electrode materials with controllable structure, specific surface area, electronic conductivity, and oxidation state, have long been highlighted. Architecture engineering of functional electrode materials toward powerful supercapacitor systems is becoming a big fashion in the community. The construction of ion-accessible tunnel structures can microscopically increase the specific capacitance and materials utilization; stiff 3D structures with high specific surface area can macroscopically assure high specific capacitance. Many exciting findings in electrode materials mainly focus on the construction of ice-folded graphene paper, in situ functionalized graphene, in situ crystallizing colloidal ionic particles and polymorphic metal oxides. This feature paper highlights some recent architecture engineering strategies toward high-energy supercapacitor electrode systems, including electric double-layer capacitance (EDLC) and pseudocapacitance.

Managing Properties of Alumina Based Granules Prepared by Disk (Dished) Molding

2019 ◽  
Vol 19 (2) ◽  
pp. 132-141 ◽  
Author(s):  
V. Yu. Kruglyakov ◽  
A. V. Glazyrin ◽  
L. A. Isupova
Keyword(s):  
Mechanical Strength ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Total Pore Volume ◽  
Mesopore Volume ◽  
Average Pore ◽  
Wood Meal ◽  
Highly Active ◽  
Average Size

Alumina-based spherical granules were prepared by disk granulation. Products of gibbsite thermoactivation in various reactors were used as the initial materials. In the course of molding, combustible additives (starch, carbon, wood meal) were added to the thermoactivated gibbsite powder, and NaOH (10 %), C2H5OH (15 %), Н3ВО3(6 %) to the wetting solution (H2O). With the product of centrifugal thermoactivation of hydrargillite, the prepared granules were stronger at the larger average size of pores; addition of NaOH, C2H5OH and H3BO3led to an increase in the specific surface area and micropore proportion but had different effects on the mechanical strength of the granules. Introduction of combustible additives (wood meal, activated carbon) affected only slightly the specific surface area, favored an increase in the total pore volume and mesopore volume, resulted in a decrease in bulk density and mechanical strength of the granules. Conditions were determined for preparation of a highly effective strong dessicant with large specific surface area (up to 340 m2/g) and average pore diameter up to 3.4 nm. Conditions were determined for preparation of strong ultramacroporous granules that are highly active to the Klaus process.

Fuels Desulphurisation by Adsorbtion on Fe / Bentonite

2017 ◽  
Vol 68 (3) ◽  
pp. 483-486
Author(s):  
Constantin Sorin Ion ◽  
Mihaela Bombos ◽  
Gabriel Vasilievici ◽  
Dorin Bombos
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Pore Volume ◽  
Pore Diameter ◽  
Adsorption Process ◽  
Continuous System ◽  
Gas Oil ◽  
Average Pore ◽  
Atmospheric Distillation

Desulfurisation of atmospheric distillation gasoline and gas oil was performed by adsorption process on Fe/ bentonite. The adsorbent was characterized by determining the adsorption isotherms, specific surface area, pore volume and average pore diameter. Adsorption experiments of atmospheric distillation gasoline and gas oil were performed in continuous system at 280�320oC, 5 atm and volume hourly space velocities of 1�2 h-1. The efficiency of adsorption on Fe / bentonite was better at desulphurisation of gasoline versus gas oil.

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