• Journal of the Korean Electrochemical Society
• /
• v.17 no.2
• /
• pp.124-129
• /
• 2014

In this article, we report the fabrication and characterization of carbon sphere/$Fe_3O_4$ nanocomposite for Li/air batteries. $Fe_3O_4$ nanoparticles are dispersed homogeneously on the surface of carbon spheres in an attempt to enhance the low conductivity of oxide catalyst ($Fe_3O_4$). The carbon sphere/$Fe_3O_4$ nanocomposite could offer wide surface area of $Fe_3O_4$ and increased carbon/catalyst contact area, which lead to enhanced catalytic activity. The electrode employing carbon sphere/$Fe_3O_4$ nanocomposite presented relatively low overpotential and stable cyclic performance compared with the electrode employing carbon sphere.

• Korean Chemical Engineering Research
• /
• v.54 no.4
• /
• pp.568-573
• /
• 2016

We investigated the charging characteristics of a conducting solid sphere (glassy carbon sphere) comparing with that of a water droplet and check the applicability of the perfect conductor theory. For the systematic research, sphere size, applied voltages, viscosity of the medium were changed and the results were compared with that of corresponding water droplets and the perfect conductor theory. Basically, a glassy carbon sphere follows the perfect conductor theory but the charging amount was lower as much as 70~80% of theoretical prediction value due to oil film formed between electrode and a carbon sphere. We hope this result provides basic understandings on the solid sphere contact charging phenomenon and related applications.

• 한국신재생에너지학회:학술대회논문집
• /
• 2011.05a
• /
• pp.221.1-221.1
• /
• 2011

In this study, we prepared the nitrogen-containing carbon spheres with mesopore processed by a facile polymerization-induced colloid aggregation method including carbonization in order to investigate the characterization and the effect on their carbon dioxide adsorption behaviors. The carbonization temperature was varied in the range of $600^{\circ}C$ to $900^{\circ}C$. The nitrogen contents of the mesoporous carbon sphere were characterized using XPS. The carbon dioxide adsorption capacities of the prepared mesoporous carbon sphere were determined by the amounts of carbon dioxide adsorptions at 298 K and 1.0 atm. The results showed that the prepared mesoporous carbons were highly effective for the carbon dioxide adsorption due to the increasing the affinity of the basic functionalities of adsorbent surface to acidic carbon dioxide. Maximum adsorption capacities of carbon dioxide at $25^{\circ}C$ were achieved up to 106 mg/g.

• Journal of Adhesion and Interface
• /
• v.15 no.2
• /
• pp.63-68
• /
• 2014

Hollow mesoporous carbon nitride material with sphere shape was synthesized using polystyrene sphere as template and cyanamide as nitrogen and carbon atom sources via thermal treatment process. The process of the silica removal is not necessary because silica as template is not in use for the synthesis of hollow mesoporous carbon nitride material and any solvents are also not in use. The size of polystyrene spheres was about 170 nm. Hollow diameter and wall thickness were 82 nm and 13 nm, respectively, in hollow mesoporous carbon nitride sphere. Surface area, mesopore size and pore volume of hollow mesoporous carbon nitride material was $188m^2g^{-1}$, 3.8 nm and $0.35cm^3g^{-1}$, respectively. The wall in hollow sphere has graphitic structure. Hollow mesoporous carbon nitride material has potential applications in the area of fuel cell, catalysis, photocatalysis, electroemmision device, etc.

• Applied Chemistry for Engineering
• /
• v.22 no.5
• /
• pp.495-500
• /
• 2011

Separation of naphthalene from pyrolyzed fuel oil, by product of Naphta cracking process (NCC) process, has been accomplished by the solvent extraction, distillation and purification process. The residual pyrolyzed fuel oil (PFO), called precursor of carbon materials, has been calcined at $300{\sim}800^{\circ}C$ in nitrogen gas to raw pitch. After the treatment of PFO by hexane and methanol, either a flake phased carbon at $350^{\circ}C$ or a carbon sphere at above $400^{\circ}C$ forms. As the calcination temperature increases, the shape of raw pitch changes from the flake phase to the sphere one, and the size of them decreases to several ${\mu}m$. Based on the BET and XRD spectrum, the carbon sphere is classified to a mesophase amorphous carbon with a cubic phase.

• Korean Journal of Medicinal Crop Science
• /
• v.8 no.1
• /
• pp.9-13
• /
• 2000

To determine the proper carbon and nitrogen sources and their proper levels for mass micro propagation of Scrophularia buergeriana Miquel, tonic and curing cough experiment were applied and a method for mass cultivation by using bioreactors (2.5 L) was expinined. Proper ratio of $NH_4NO_3\;:\;$KNO_3$ was 413 mg/L : 1900 mg/L for multiple shoot production. Sucrose was more effective than glucose or fractose as carbon source and 3% concentration was good for shoot formation. Total nitrogen was not detected after six weeks both in 500 ml flask and bioreactor culture. Sucrose was decreased sharply after two weeks and there was no sucrose left after three weeks both in 500 ml flask and bioreactor culture. The stirrer in bioreactor caused shear stress to shoots severely. The sphere type bioreactor was better than the cylinder type and removal of inner loop in sphere type was more effective to avoid shear stress.

• Journal of Photoscience
• /
• v.11 no.1
• /
• pp.11-17
• /
• 2004

Fluorescence quenching of l,4-bis [2-(2-methylphenyl) ethenyl]-benzene (Bis-MSB) by carbon tetrachloride in five different solvents namely hexane, cyclohexane, toluene, benzene and dioxane has been carried out at room temperature with a view to understand the quenching mechanisms. The Stern-Volmer plot has been found to be non-linear with a positive deviation for all the solvents studied. In order to interpret these results we have invoked the Ground state complex and Sphere of action static quenching models. Using these models various rate parameters have been determined. The magnitudes of these parameters imply that sphere of action static quenching model agrees well with the experimental results. Hence the positive deviation in the Stem-Volmer plots is attributed to the static and dynamic quenching. Further, with the use of Finite Sink approximation model, it was possible to check whether these bimolecular reactions as diffusion limited and to estimate independently distance parameter R' and mutual diffusion coefficient D. Finally an effort has been made to correlate the values of R'and D with the values of the encounter distance R and the mutual diffusion coefficient D determined using the Edwardis empirical relation and Stokes-Einstein relation.

• Journal of the Korean Electrochemical Society
• /
• v.24 no.3
• /
• pp.42-51
• /
• 2021

Dissociation into Lithium-polysulfide electrolyte due to repeated cycles during the Lithium/Sulfur battery reaction is a major problem of reduced battery lifespan. We searched for a porous carbon with a large specific surface area that infiltrated S to prevent liquid Lithium-polysulfide from being dissolved in electrolyte, induce adsorption of Lithium-polysulfide, and further increase conductivity. In order to obtain porous carbon spheres with a large specific surface area, the carbon spheres of 1939 m²/g were raised to 2200 m²/g through additional KOH treatment. In addition, through heat treatment with S, a carbon sulfur compound containing 75 wt% of S was fabricate and material analysis was conducted on the possibility of using the cathode material. The electrochemical characteristics of the Reference (622; sulfur: 60%, conductive material: 20%, binder: 20%) pouch cell and the pouch cell made using 75wt% of carbon sulfur compound were analyzed. 75wt% of carbon sulfur pouch cell showed a 20% increase in lifespan and 10% improvement in C-rate compared to the Reference pouch cell after 50 cycles.

• Journal of the Korean Electrochemical Society
• /
• v.10 no.4
• /
• pp.252-256
• /
• 2007

A series of spherical porous carbons were prepared via resorcinol-formaldehyde (RF) sol-gel polymerization in the presence of cationic surfactant (CTAB, cetyltrimethylammonium bromide), wherein the carbon sphere size was controlled by varying the CTAB introduction time after a pre-determined period of addition reaction (termed as "pre-curing"). The sphere size gradually decreases with an increase in the pre-curing time within the range of 30-150 nm. The carbons possess two types of pores; one inside carbon spheres (intra-particle pores) and the other at the interstitial sites made by carbon spheres (inter-particle pores). Of the two, the surface exposed on the former was dominant to determine the electric double-layer capacitor (EDLC) performance of porous carbons. As the intra-particle pores were generated inside RF gel spheres by gasification, the pore diameter was similar for all these carbons, thereby the pore length turned out to be a decisive factor controlling the EDLC performance. The charge-discharge voltage profiles and complex capacitance analysis consistently illustrate that the smaller-sized RF carbons deliver a better rate capability, which must be the direct result of facilitated ion penetration into shorter pores.

• Korean Chemical Engineering Research
• /
• v.48 no.4
• /
• pp.423-427
• /
• 2010

Carbon nano sphere(CNS) and nano bowl of carbon(NBC) containing 1.0 wt% copper were prepared by impregnation method and their catalytic activity was compared in the phenol hydroxylation with hydrogen peroxide in the presence of water and acetonitrile as a solvent, respectively. Cu content of catalysts was determined by EDS, and BET, pore volume, pore size and pore size distribution were compared. For both catalysts, phenol conversion, $H_2O_2$ efficiency and yield of catechol and hydroquinone were higher in the presence of water as a solvent than those in the presence of actonitrile. And catalytic activity such as phenol conversion and $H_2O_2$ efficiency of 1.0 Cu/CNS is about two times higher than that of 1.0 Cu/NBC in water solvent.