• Bulletin of the Korean Chemical Society
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• v.31 no.2
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• pp.351-354
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• 2010

Nickel nanoparticles (Ni NPs) appeared to exhibit the catalytic activity in one-pot cyclocondensation reaction for the preparation of 3,4-dihydropyrimidine-2(1H)-ones via Biginelli reaction from aromatic/heteroaromatic/aliphatic aldehydes, urea/thiourea and ethyl acetoacetate under microwave irradiation has been described. The UV absorbance spectra showed metallic Ni characteristics and appreciate with the particle size determined by Transmission electron microscopy (TEM). After reaction course the Ni NPs can be re-covered and reused without any apparent loss of activity.

• Vacuum Magazine
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• v.3 no.1
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• pp.4-8
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• 2016

Motivated by two dimensional graphene, layered transition metal dichalcogenides (TMDs) have attracted scientific interests by their diverse electronic, optical and catalytic properties. In particular, group 6 TMDs such as $MoS_2$ and $MoTe_2$ have polymorphs (with metallic octahedral and semiconducting hexagonal phases) which are not present in graphene. Here, we introduce a new concept in 2D materials' studies, structural phase transition, with group 6 TMDs and its current research trend and applications for electric device and electrochemical catalyst.

• Carbon letters
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• v.8 no.4
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• pp.307-312
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• 2007

A method for evaluating bulk sensitive structural characteristics of unpurified, as-purified, and acid treated single walled carbon nanotubes (SWNTs) was described in the present study. The optical spectra of SWNT solutions were well resolved after prolonged sonication and they were correlated to the diameter and the distribution of nanotubes. The acid-treated SWNTs were similar to as-purified SWNTs in terms of catalyst residue, radial breathing mode (RBM) in the Raman spectra, and the first band gap energy of semiconducting tubes in the optical spectra. The solution phase optical spectra were more sensitive to changes in the small diameter and metallic tubes after the acid treatment than were the RBM spectra.

• Particle and aerosol research
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• v.8 no.2
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• pp.69-74
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• 2012

This study describes how successfully a conventional flame aerosol synthesis was used to continuously synthesize Pt-Ru catalysts supported by carbon agglomerates. Nearly spherical catalysts produced in the flame were mainly composed of metallic Pt and Ru with the molar ratio of 1:1 and those sizes were controllable from ~1.5 nm to ~2.0 nm. Nevertheless, only Pt peaks were found from X-ray diffraction experiments, suggesting that amorphous-like Ru was well mixed in the crystalline Pt lattices. It was found from Cyclo-voltamograms and CO stripping experiments that the electrochemical properties of the catalysts are at least comparable to that of a conventional commercial sample.

• Korean Chemical Engineering Research
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• v.55 no.2
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• pp.156-162
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• 2017

CuO(x)/0.3Al-0.7Ce catalysts with different CuO loadings (x = 2~20 wt%) were prepared by impregnation method and investigated the effects of CuO loadings on the low temperature CO oxidation. Of the used catalysts, the CuO(10)/0.3Al-0.7Ce catalyst showed the highest catalytic performance in the absence or presence of water vapor. In the presence of water vapor, the catalytic performance was drastically decreased, with a temperature of 50% CO conversion ($T_{50%}$) shifted to higher temperature by $50^{\circ}C$ compared to the those in dry conditions because of the competitive adsorption of water vapor on the active sites. The copper metal surface area calculated from $N_2O$-titration analysis and the oxygen capacity from CO-pulse experiments were increased with the CuO loadings and showed a maximum at 10 wt%CuO/0.3Al-0.7Ce catalyst. These trends are in good agreement with the tendency of $T_{50%}$ of the catalysts. From these characteristic aspects, it could be deduced that the catalytic performance was closely related to the oxygen capacity and the copper metallic surface area.

• Korean Journal of Materials Research
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• v.26 no.5
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• pp.250-257
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• 2016

Octahedral $Co_3O_4$/carbon nanofiber (CNF) composites are fabricated using electrospinning and hydrothermal methods. Their morphological characteristics, chemical bonding states, and electrochemical properties are used to demonstrate the improved photovoltaic properties of the samples. Octahedral $Co_3O_4$ grown on CNFs is based on metallic Co nanoparticles acting as seeds in the CNFs, which seeds are directly related to the high performance of DSSCs. The octahedral $Co_3O_4$/CNFs composites exhibit high photocurrent density ($12.73mA/m^2$), superb fill factor (62.1 %), and excellent power conversion efficiency (5.61 %) compared to those characteristics of commercial $Co_3O_4$, conventional CNFs, and metallic Co-seed/CNFs. These results can be described as stemmnig from the synergistic effect of the porous and graphitized matrix formed by catalytic graphitization using the metal cobalt catalyst on CNFs, which leads to an increase in the catalytic activity for the reduction of triiodide ions. Therefore, octahedral $Co_3O_4$/CNFs composites can be used as a counter electrode for Pt-free dye-sensitized solar cells.

• Journal of the Korean Applied Science and Technology
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• v.28 no.3
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• pp.321-328
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• 2011

The autothermal reforming reaction of methane was investigated to produce hyd rogen with Ni/$CeO_2-ZrO_2$, Ni/$Al_2O_3$-MgO and Ni-Ru/$Al_2O_3$-MgO catalysts. Honeycomb metalli c monolith was applied in order to obtain high catalytic activity and stability in autothermal r eforming. The catalysts were characterized by XRD, BET and SEM. The influence of various catalysts on hydrogen production was studied for the feed ratio($O_2/CH_4$, $H_2O/CH_4$). The $O_2/CH_4$ and $H_2O/CH_4$ ratio governed the methane conversion and temperature profile of reactor. Th e reactor temperature increased as the reaction shifted from endothermic to exothermic reactio n with increasing $O_2/CH_4$ ratio. Among the catalysts used in the experiment, the Ni-Ru/$Al_2O_3$-MgO catalyst showed the highest activity. The 60% of $CH_4$ conversion was obtained, and th e reactor temperature was maintained $600^{\circ}C$ at the condition of GHSV=$10000h^{-1}$ and feed ratio S/C/O=0.5/1/0.5.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.402.1-402.1
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• 2016

The performance of solid oxide fuel cells (SOFCs) is directly related to the electrocatalytic activity of composite electrodes in which triple phase boundaries (TPBs) of metallic catalyst, oxygen ion conducting support, and gas should be three-dimensionally maximized. The distribution morphology of catalytic nanoparticle dispersed on external surfaces is of key importance for maximized TPBs. Herein in situ grown nickel nanoparticle onto the surface of fluorite oxide is demonstrated employing gadolium-nickel co-doped ceria ($Gd0.2-xNixCe0.8O2-{\delta}$, GNDC) by reductive annealing. GNDC powders were synthesized via a Pechini-type sol-gel process while maximum doping ratio of Ni into the cerium oxide was defined by X-ray diffraction. Subsequently, NiO-GNDC composite were screen printed on the both sides of yttrium-stabilized zirconia (YSZ) pellet to fabricate the symmetrical half cells. Electrochemical impedance spectroscopy (EIS) showed that the polarization resistance was decreased when it was compared to conventional Ni-GDC anode and this effect became greater at lower temperature. Ex situ microstructural analysis using scanning electron microscopy after the reductive annealing exhibited the exsolution of Ni nanoparticles on the fluorite phases. The influence of Ni contents in GNDC on polarization characteristics of anodes were examined by EIS under H2/H2O atmosphere. Finally, the addition of optimized GNDC into the anode functional layer (AFL) dramatically enhanced cell performance of anode-supported coin cells.

• Applied Chemistry for Engineering
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• v.5 no.6
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• pp.925-934
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• 1994

Nickel recovered from the spent oil-hydrogenation catalysts was used in hydrogenation catalyst preparation. The spent catalyst contains approximately 21.8% Ni, 0.7% Mg, and small quantities of Al, Fe, and Zn. Nickel recovery was obtained by inorganic acid digestion in the order of HCI>$NHO_3$>$H_2SO_4$. For $HNO_3$, 3hour extraction with 3N solution was satisfactory. In the PH range of 6.5~9.0, Ni recovery was higher, but metallic impurities were found to be coprecipitated. The PH in the range of 7.0~9.0 seems to be the optimum condition for separation to obtain acceptable Ni precipitates without the decrease of purity. The catalysts prepared with reclaimed nickel by wet reduction methods showed catalytic activities close to those prepared using reagent nickel in the oil hydrogenation reaction. The surface areas of the support do not seem to affect the catalytic activity.

• 한국신재생에너지학회:학술대회논문집
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• 2009.11a
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• pp.171-171
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• 2009

The electrodes are usually made of a porous mixture of carbon-supported platinum and ionomers. $SnO_2$ particles provide as supports that have been used for DMFCs, and it have high catalytic activities toward methanol oxidation. The main advantage of $SnO_2$ supported electrodes is that it has strong chemical interactions with metallic components. The high activity to a synergistic bifunctional mechanism in which Pt provides the adsorption sites for CO, while oxygen adsorbs dissociative on $SnO_2$. The reaction between the adsorbed species occurs at the Pt/$SnO_2$ boundary. The morphological observations were characterized by FESEM and transmission electron microscopy (TEM). $SnO_2$ particles crystallinity was analyzed by the X-ray diffraction (XRD). The surface bonded state of the $SnO_2$ particles and electrode materials were observed by the X-ray photoelectron spectroscopy (XPS). The electric properties of the Pt/$SnO_2$ catalyst for methanol oxidation have been investigated by the cyclic voltametry (CV) in 0.1M $H_2SO_4$ and 0.1M MeOH aqueous solution. The peak current density of methanol oxidation was increased as the $SnO_2$ content in the anode catalysts increased. Pt/$SnO_2$ catalysts improve the removal of CO ads species formed on the platinum surface during methanol electro-oxidation.