• Applied Chemistry for Engineering
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• v.18 no.6
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• pp.618-624
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• 2007

thermochemical methane reforming consisting of two steps on Cu/Fe/Zr mixed oxide media was carried out using a fixed bed infrared reactor. In the first step, the metal oxide was reduced with methane to produce CO, $H_2$ and the reduced metal oxide in the temperature of 1173 K. In the second step, the reduced metal oxide was re-oxidized with steam to produce $H_2$ and the metal oxide in the temperature of 973 K. The reaction characteristics on the added amounts of Cu in Cu/Fe/Zr mixed oxide media and the cyclic tests were evaluated. With the increase of the added amount of Cu in Cu/Fe/Zr mixed oxide media, the conversion of $CH_4$, the selectivity of $CO_2$ and the $H_2/CO$ molar ratio were increased, while the selectivity of CO was decreased in the first step. On the other hand, the evolved amount of $H_2$ was decreased with increasing the added amount of Cu in the second step. The $Cu_xFe_{3-x}O_4/ZrO_2$ medium added with Cu of x = 0.7 showed good regeneration properties in the 10th cyclic tests indicating that the medium had high durability. In addition, the gasification of the deposited carbon in the water splitting step was promoted with the addition of Cu in the media.

• Journal of the Korean institute of surface engineering
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• v.45 no.6
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• pp.248-256
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• 2012

A Pd-based hydrogen membranes for hydrogen purification and separation need high hydrogen perm-selectivity. The surface roughness of the support is important to coat the pinholes free and thin-film membrane over it. Also, The pinholes drastically decreased the hydrogen perm-selectivity of the Pd-based composite membrane. In order to remove the pinholes, we introduced various surface pre-treatment such as alumina powder packing, nickel electro-plating and micro-polishing pre-treatment. Especially, the micro-polishing pretreatment was very effective in roughness leveling off the surface of the porous nickel support, and it almost completely plugged the pores. Fine Ni particles filled surface pinholes with could form open structure at the interface of Pd alloy coating and Ni support by their diffusion to the membrane and resintering. In this study, a $4{\mu}m$ surface pore-free Pd-Cu-Ni ternary alloy membrane on a porous nickel substrate was successfully prepared by micro-polishing, high temperature sputtering and Cu-reflow process. And $H_2$ permeation and $N_2$ leak tests showed that the Pd-Cu-Ni ternary alloy hydrogen membrane achieved both high permeability of $13.2ml{\cdot}cm^{-2}{\cdot}min^{-1}{\cdot}atm^{-1}$ permation flux and infinite selectivity.

• Journal of the Korean Ceramic Society
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• v.47 no.1
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• pp.92-96
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• 2010

Based on the differential electrode equilibria approach, potentiometric YSZ sensors with semiconducting oxide electrodes for CO detection are developed. To improve the selectivity, sensitivity and response-time of the sensor, our strategy includes (a) selection of an oxide with a semiconducting response to CO, (b) addition of other semiconducting materials, (c) addition of a catalyst (Pd), (d) utilization of combined p- and n-type electrodes in one sensor configuration, and (e) optimization of operating temperatures. Excellent sensing performance is obtained by a novel device structure incorporating $La_2CuO_4$ electrodes on one side and $TiO_2$-based electrodes on opposite substrate faces with Pt contacts. The resulting response produces additive effects for the individual $La_2CuO_4$ and $TiO_2$-based electrodes voltages, thereby realizing an even higher CO sensitivity. The device also is highly selective to CO versus NO with minor sensitivity for NO concentration, compared to a notably large CO sensitivity.

• Bulletin of the Korean Chemical Society
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• v.25 no.6
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• pp.869-872
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• 2004

Newly synthesized 8-hydroxyquinoline based benzothiazole derivative 2 showed a distinctive $Hg^{2+}$-selectivity over other transition metal ions in aqueous solution. The fluorescence emission at 455 nm of 2 was completely quenched upon interaction with $Hg^{2+}$ ions in dioxane-$H_2O$ system (9 : 1, v/v). The selectivity was decreased in the order of $Hg^{2+}\;>>\;Cu^{2+}\;>\;Cd^{2+}\;>\;Pb^{2+}\;{\thickapprox}\;Zn^{2+}\;{\thickapprox}\;Ni^{2+},\;and\;Hg^{2+}$ concentration dependent fluorescence quenching profile was observed in the presence of common interfering metal ions as background. The fluorescence behavior of 2 suggests that the prepared compound could be used as a fluorescent signaling subunit for the construction of new $Hg^{2+}$-sensitive ON-OFF type supramolecular switching systems.

• Advances in environmental research
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• v.5 no.1
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• pp.51-59
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• 2016

In this study, nitrate reduction of real groundwater sample by 2.2%Cu-1.6%Pd-hematite catalyst was evaluated at different nitrate concentrations, catalyst concentrations, and recycling. Results show that the nitrate reduction is improved by increasing the catalyst concentration. Specific nitrate removal by 2.2%Cu-1.6%Pd-hematite increased linearly with the increase of nitrate concentration showing that the catalyst possesses significantly higher reduction capacity. More than 95% nitrate reduction was observed over five recycles by 2.2%Cu-1.6%Pd-hematite with ~56% nitrogen selectivity in all recycling batches. The results from this study indicate that stable reduction of nitrate in groundwater can be achieved by 2.2%Cu-1.6%Pd-hematite over the wide range of initial nitrate inputs.

• Bulletin of the Korean Chemical Society
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• v.35 no.1
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• pp.141-146
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• 2014

A series of bimetallic Cu-Zn/$SiO_2$ catalysts were prepared via thermal decomposition of the as-synthesized $CuZn(OH)_4(H_2SiO_3)_2{\cdot}nH_2O$ hydroxides precursors. This highly dispersed Cu-solid base catalyst is extremely effective for hydrogenation of ethyl acetate to ethanol. The reduction and oxidation features of the precursors prepared by coprecipitation method and catalysts were extensively investigated by TGA, XRD, TPR and $N_2$-adsorption techniques. Catalytic activity by ethyl acetate hydrogenation of reaction temperatures between 120 and $300^{\circ}C$, different catalyst calcination and reduction temperatures, different Cu/Zn loadings have been examined extensively. The relation between the performance for hydrogenation of ethyl acetate and the structure of the Cu-solid base catalysts with Zn loading were discussed. The detected conversion of ethyl acetate reached 81.6% with a 93.8% selectivity of ethanol. This investigation of the Cu-Zn/$SiO_2$ catalyst provides a recently proposed pathway for ethyl acetate hydrogenation reaction to produce ethanol over Cu-solid base catalysts.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.12
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• pp.1626-1632
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• 2018

In this paper, we describe the fabrication and characterization of a hydrogen peroxide ($H_2O_2$) sensor based on palladium and copper (PdCu) electroplated laser induced graphene (LIG) electrodes. $CO_2$ laser was used to form LIG electrodes on a PI film. This fabrication method allows simple control of the LIG electrode size and shape. The PdCu was electrochemically deposited on the LIG electrodes to improve the electrocatalytic reaction with $H_2O_2$. The electrochemical performance of this sensor was evaluated in terms of selectivity, sensitivity, and linearity. The physical characterization of this sensor was conducted using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS), which confirmed that PdCu was formed on the laser induced graphene electrode. In order to increase the sensor sensitivity, the Pd:Cu ratio of the electroplated PdCu was varied to five different values and the condition of highest amperometric current at an identical of $H_2O_2$ concentration was chosen among them. The resulting amperometric current was highest when the ratio of Pd:Cu was 7:3 and this Pd;Cu ratio was employed in the sensor fabrication. The fabricated PdCu/LIG electrode based $H_2O_2$ sensor exhibited a sensitivity of $139.4{\mu}A/mM{\cdot}cm^2$, a broad linear range between 0 mM and 16 mM of $H_2O_2$ concentrations at applied potential of -0.15 V, and high reproducibility (RSD = 2.6%). The selectivity of the fabricated sensors was also evaluated by applying ascorbic acid, glucose, and lactose separately onto the sensor in order to see if the sensor ourput is affected by one of them and the sensor output was not affected. In conclusion, the proposed PdCu/LIG electrode based $H_2O_2$ sensor seems to be suitable $H_2O_2$ sensor in various applications.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2011.03a
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• pp.68-68
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• 2011

A new chemosensor based on rhodamine B (1) for $Hg^{2+}$ and $Cu^{2+}$ was synthesized by one-step condensation reaction of rhodamine B hydrazide and Azo dye. Studying for its fluorogenic and colorimetric behaviors towards various metal ions, extreme sensitivity and selectivity were achieved by the detection of $Hg^{2+}$ and $Cu^{2+}$ over other commonly coexistent metal ions, which were accompanied by ring opening of a rhodamine spirocycle framework. In acetonitrile, the presence of $Hg^{2+}$ and $Cu^{2+}$ induces the formation of a Dye 1-ion complex, which was deduced by spectroscopy.

• Bulletin of the Korean Chemical Society
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• v.26 no.5
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• pp.849-851
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• 2005

• Journal of the Microelectronics and Packaging Society
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• v.27 no.4
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• pp.11-17
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• 2020

Copper has been proved to be the best catalyst for electrochemical CO2 reduction reaction, however, for optimal efficiency and selectivity, its performance requires improvements. Electrochemical CO2 reduction reaction (RR) using CuO nanowire electrode was performed with different concentrations of KHCO3 electrolyte (0.1 M, 0.5 M, and 1 M). Cu(OH)2 was formed on Cu foil, followed by thermal-treatment at 200℃ under the air atmosphere for 2 hrs to transform it to the crystalline phase of CuO. We evaluated the effects of different KHCO3 electrolyte concentrations on electrochemical CO2 reduction reaction (RR) using the CuO nanowire electrode. At a constant current (5mA), low concentrated bicarbonate exhibited a more negative potential -0.77 V vs. Reversible Hydrogen Electrode (RHE) (briefly abbreviated as VRHE), while the negative potential reduced to -0.33 VRHE in the high concentration of bicarbonate solution. Production of H2 and CH4 increased with an increased concentration of electrolyte (KHCO3). CH4 production efficiency was high at low negative potential whereas HCOOH was not influenced by bicarbonate concentration. Our study provides insights into efficient, economically viable, and sustainable methods of mitigating the harmful environmental effects of CO2 emission.