Highly enhanced sorption properties of heteroatom-doped porous carbon spheres

유원철 한국공업화학회 2016 한국공업화학회 연구논문 초록집 Vol.2016 No.0

Highly enhanced CO2 and H2 adsorption properties, and a selective adsorption of CO2 over N2 were achieved from a series of different phenolic resin-based carbon spheres (resorcinol-formaldehyde carbon (RFC) and phenol-formaldehyde carbon (PFC)), and melanin carbon spheres, respectively. RFC, PFC, and MC were produced by carbonization of RF and PF polymer (RFP and PFP), and melanin polymer (MP) spheres synthesized sol-gel reaction method and subsequent activations with hot CO2 and NH3 gas treatments. A series of CO2-activated and N-doped RFC and PFC spheres show almost perfect correlation between CO2 adsorption capacities and fine micropores. Moreover, prolonged activation processes for RFC and PFC spheres showing an ultra-high surface area with the highly H2 uptake capacity. In addition, melanin carbon (MC) spheres represent highly selective adsorption capacities for CO2 over N2, probably due to the increased chemisorption effect from the hetero-atom doped MC spheres.

Study of the structure-properties relations of carbon spheres affecting electrochemical performances of EDLCs

Kim, Hee Soo,Abbas, Muhammad Awais,Kang, Min Seok,Kyung, Hyuna,Bang, Jin Ho,Yoo, Won Cheol Elsevier 2019 ELECTROCHIMICA ACTA Vol.304 No.-

<P><B>Abstract</B></P> <P>For high performance of electrical double layer capacitors (EDLCs), a high specific surface area (SSA) and N-doping level, and small particle size of carbonaceous materials, have been believed to be crucial factors. However, there have been few reports on simultaneous study of the structure-properties relations of carbons and the electrochemical performances of EDLCs. Herein, we report the relationship between the structural properties of carbons, such as the SSA, N-doping, and particle size, and the electrochemical properties of EDLCs by using a series of well-defined carbons. Monodisperse and size-tunable resorcinol-formaldehyde carbon (RFC) spheres were synthesized and activated by hot CO<SUB>2</SUB> treatment to increase the SSA up to 3958 m<SUP>2</SUP>/g (RFC_C390 sample). When the specific capacitances of the RFC spheres were plotted in terms of their SSAs, an almost perfect correlation (R<SUP>2</SUP> = 0.99) was observed, which confirmed the linear relationship between the specific capacitance and the SSA. In addition, N-doped melanin C (MC) spheres were synthesized and subsequently activated for N-doping effect. Activated MC (MC_C130), which exhibited similar SSA (2618 m<SUP>2</SUP>/g) and size (301 nm) but a different N-doping level (3.1%) compared with those (2793 m<SUP>2</SUP>/g, 312 nm, and 1.3%, respectively) of the activated RFC spheres (RFC_C120), displayed higher specific capacitance (288 F/g), capacitance retention (64%), and long term stability over 5000 cycles (93%) compared with those (260 F/g, 58%, and 90%, respectively) of the RFC counterparts. To observe the particle size effect, different sizes (98, 280, and 579 nm) of RFC spheres with similar SSAs (3981, 3958, and 3898 m<SUP>2</SUP>/g, respectively) and pore size distributions were prepared, such that the smallest RFC revealed the best EDLC performance in terms of specific capacitance (360 F/g), capacitance retention (70%), and long term stability over 5000 cycles (98%), all of which could be compared with the values reported in the literature. Furthermore, all of the Carbon samples were analyzed by using electrochemical impedance spectroscopy for confirming the structure-properties relations of carbon spheres with the electrochemical performances of EDLCs.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Monodisperse and size-tunable carbon spheres were synthesized and activated by hot CO<SUB>2</SUB> treatment. </LI> <LI> Structure-properties relations of carbon spheres with electrochemical performance of EDLCs were elucidated. </LI> <LI> EIS study also supported the relationship of structure-properties of carbon and EDLC performances. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Monodispersed N-Doped Carbon Nanospheres for Supercapacitor Application

Lee, Whon-hee,Moon, Jun Hyuk American Chemical Society 2014 ACS APPLIED MATERIALS & INTERFACES Vol.6 No.16

<P>Highly monodispersed nitrogen-doped carbon nanospheres are prepared by the pyrolytic carbonization of emulsion-polymerized polystyrene-based colloidal spheres in the presence of a nitrogen-enriched molecule, melamine (1,3,5-triazine-2,4,6-triamine). The nitrogen-doped carbon spheres are successfully tested for use as electrode materials in supercapacitors. The nitrogen content incorporated into the carbon sphere is controlled by changing the weight ratio of melamine to the polymer spheres. The nitrogen doping concentration is proportional to the mixing weight ratio. The nitrogen doping produces relatively abundant pyridinic and pyrrolic configurations, and these configurations are observed to be more abundant for carbon spheres with high nitrogen doping. The nitrogen doping enhances the pseudocapacitance and the electrical conductivity of carbon, thereby enhancing the specific capacitance. We obtain a specific capacitance of up to 191.9 F g<SUP>–1</SUP> with 20% nitrogen doped carbon nanospheres, which is 14 times higher than that of the undoped carbon nanospheres. Moreover, the capacitance retention remains up to 10 000 cycles, which clearly displays a good cycling stability the nitrogen-doped carbon nanospheres as the supercapacitve electrode materials.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/aamick/2014/aamick.2014.6.issue-16/am5033378/production/images/medium/am-2014-033378_0007.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/am5033378'>ACS Electronic Supporting Info</A></P>

Light scattering enhanced photoanodes for dye-sensitized solar cells prepared by carbon spheres/TiO_2 nanoparticle composites

Guangtao Yang,Jing Zhang,Peiqing Wang,Qiang Sun,Jun Zheng,Yuejin Zhu 한국물리학회 2011 Current Applied Physics Vol.11 No.3

Incorporating scattering centers in the nanocrystalline photoanode or additional scattering layers on the nanocrystalline photoanode is an effective way to enhance the light harvest efficiency (LHE) of the photoanode and the performance of dye-sensitized solar cells (DSSCs). In this work, mesoporous photoanodes were fabricated based on the composites of anatase TiO_2 nanoparticles and carbon spheres. The holes were left after calcination thus serving as the light scattering centers in the photoanode. The size and the amounts of the holes were adjusted by changing the size (250, 500 and 700 nm) and concentration (5, 10, 15 and 20 wt% of the TiO_2 nanocrystallines) of the carbon spheres in the slurry. The light scattering ability and the dye adsorption of the photoanodes with holes of varied size and contents were investigated. The holes left by calcinating the carbon spheres increased the light scattering of the photoanode. However, the increased light scattering ability offset the dye adsorption ability of the photoanode by high amounts of carbon spheres modification. The performances of the DSSCs are investigated under the simulated sunlight and the incident light (400―780 nm). The DSSC with photoanode made from the slurry with 500 nm and 15 wt% carbon spheres exhibited the opitimized performance (Jsc = 14.8 mA cm^-2, Voc = 0.657 V, FF = 0.703 and η = 7.2%), much better than the DSSCs with photoanode made by the pure TiO_2 nanocrystalline (Jsc = 11.7 mA cm^-2, Voc = 0.645V, FF = 0.699 and η = 5.55%) and other photoanodes, indicating it best balanced the controversy of the enhanced light scattering ability and the decreased dye adsorption. The incident-photo-to-electric conversion efficiency test indicated the highest LHE of the 500 nm and 15 wt% carbon spheres modified photoanode.

Complementary surface modification by disordered carbon and reduced graphene oxide on SnO₂ hollow spheres as an anode for Li-ion battery

Woo, Hyungsub,Wi, Sungun,Kim, Jaewon,Kim, Jinhyun,Lee, Sangheon,Hwang, Taehyun,Kang, Joonhyeon,Kim, Jaewook,Park, Kimin,Gil, Bumjin,Nam, Seunghoon,Park, Byungwoo Elsevier 2018 Carbon Vol.129 No.-

<P><B>Abstract</B></P> <P>Among the efforts to apply SnO<SUB>2</SUB> as an anode, the adoption of carbonaceous materials has been considered as a decent strategy to mitigate volume expansion problem (∼300%) during cycling. Nevertheless, it still needs in-depth examinations to identify the individual role of each coating material and further improvements for practical applications. To understand the underlying correlations of various carbon coatings with electrochemical performance of active materials, disordered carbon and reduced graphene oxide (RGO) are selectively used for SnO<SUB>2</SUB> hollow spheres. The disordered carbon, which covered the surfaces of and voids between the primary particles, acts as a buffer layer for volume expansion, and the RGO, that interconnected the hollow secondary particles, provides a 2D-electronic path to the electrode. Finally, both of them are utilized on the SnO<SUB>2</SUB> hollow spheres, namely the double coating is conducted from the expectation of synergistic effects, and it successfully exhibits a moderate capacity after 100 cycles even at 1 C with a low carbon content (7.7 wt. %). The essential factors that are inherently present and thereby significantly affect the electrochemical performance of the SnO<SUB>2</SUB> electrode are successfully identified by a facile dual-carbon modification, so that this strategy will be applicable to other potential active materials.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Preparation and Characterization of Molecular Sieving Carbon by Methane and Benzene Cracking over Activated Carbon Shperes

Harish Chandra Joshi,Rajesh Kumar,Rohitashaw Kumar Singh,Darshan Lal 한국탄소학회 2007 Carbon Letters Vol.8 No.1

Molecular sieving carbon (MSC) for separating O2-N2 and CO2-CH4 has been prepared through chemical vapor deposition(CVD) of methane and benzene on activated carbon spheres (ACS) derived from polystyrene sulfonate beads. The validity ofthe material for assesment of molecular sieving behavior for O2-N2 and CO2-CH4 pair of gases was assessed by the kineticadsorption of the corresponding gases at 25oC. It was observed that methane cracking on ACS lead to deposition of carbonmostly in whole length of pores rather than in pore entrance, resulting in a reduction in adsorption capacity. MSC showinggood selectivity for CO2-CH4 and O2-N2 separation was obtained through benzene cracking on ACS with benzene entrantmentof 0.40×104 g/ml at cracking temperature of 725oC for a period of 90 minutes resulting in a selectivity of 3.31:1.00 for O2-N2and 8.00:1.00 for CO2-CH4 pair of gases respectively.

Carbon sphere as a black pigment for an electronic paper

Kang Uk Lee,Kyung Ju Park,권오중,김재정 한국물리학회 2013 Current Applied Physics Vol.13 No.2

electronic paper due to its non-uniform structure. Carbon spheres, with spherical shape and relatively narrow size distribution, are expected to overcome this limitation and substitute for carbon black in the electronic paper. Carbon spheres were synthesized through a hydrothermal reaction using glucose as a raw material. By controlling reaction time and glucose concentration, appropriate non-agglomerated carbon spheres with an average diameter of 202.26 (±26.15) nm were fabricated. To increase their dispersibility in dielectric fluid, p-(2-ethylhexyl acrylate) was grafted onto the surface of the carbon spheres. Then, acid and base charge control agents were mixed with the carbon spheres to produce a pigment with higher mobility in the dielectric fluid. The optimized combination of pigment, charge control agent and solvent reveals reasonably fast switching time of about 540 ms.

Carbon complex supported nano-catalysts for gas-to-liquids

하경수,임제미,김대각,이진우,김태완 한국공업화학회 2016 한국공업화학회 연구논문 초록집 Vol.2016 No.0

A hexagonally ordered mesoporous carbon (OMC) and other materials were utilized as supports for Fischer-Tropsch catalysts. Each array of elongated pore structure with metal nanoparticles can be regarded as a nanochannel reactor. Due to the pore confinement and the hydrophobic nature of the OMC, this catalyst demonstrated the excellent catalytic performance for synthetic fuels. Regarding non-porous carbon sphere supported Rh catalyst, FT-IR spectroscopy of adsorbed CO has revealed the presence of linearly bonded CO at Rh0 sites and gem dicarbonyl species at Rh+ sites, which are crucial to chain growth and oxygenate formation, in promoted Rh catalysts encapsulated in carbon spheres. Although syngas-to-alcohols technology has focused primarily on production of ethanol, this study has shown that carbon spheres and ordered mesoporous carbon supports enhance CO adsorption and selective production of C3 and C4 alcohols as well as ethanol.

Carbon Sphere@Nickel sulfide core-shell nanocomposite for high performance supercapacitor application

A. Simon Justin,P. Vickraman,B. Joji Reddy 한국물리학회 2019 Current Applied Physics Vol.19 No.3

The Carbon sphere@Nickel sulfide core-shell nanocomposites for different mole ratios of Carbon sphere (0:1; 0.5:1 and 1:1) have been synthesized by a facile low temperature water-bath method without any further calcination. XRD studies on the core-shell nanocomposites show that characteristic peaks associated with rhombohedral phase structure of nickel sulfide have been retained. TEM morphology presents the interlinked coreshell of Carbon sphere@Nickel sulfide composite with grass-leaf dexterity for better ionic diffusion. BET study confirms the formation of mesoporous structure with high surface area. The existence of elements and its electronic configuration is noted through XPS. The electrochemical studies on pristine nickel sulfide and its Carbon sphere@Nickel sulfide core-shell composites reveal that Carbon sphere@Nickel sulfide (0.5:1) exhibits high specific capacitance of 1022 F g−1 at a current density of 1 A g−1. It shows good cyclic performance even beyond 4000 consecutive charge/discharge cycles at a relatively high current density of 20 A g−1 with the ∼83% of retention.

Characteristics of sphere active carbon derived from glucose compound by hydrothermal method

허근,육영재,박수길 한국공업화학회 2015 한국공업화학회 연구논문 초록집 Vol.2015 No.1

The EDLC’s electrode are consisted of electrical conductor, binder and active material. Among of them, active materials are generally used carbon materials because of using carbon materials are easy to get and have low price with high electrical conductivity. This research show that the activ carbon was obtained with sphere shape from dextrose glucose through the hydrothermal carbonization process and K₂CO₃ activation steps. We measured electrochemical characteristics through Impedance and CV. Also, active carbon's morphology was examined using SEM and specific surface area had been examined using BET analysis.