• Journal of Climate Change Research
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• v.7 no.3
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• pp.231-236
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• 2016

Electrocatalytic reduction can produce useful chemicals and fuels such as carbon monoxide, methane, formate, aldehydes, and alcohols using carbon dioxide, the green house gas, as a reactant through the supply of electrical energy. In this study, tin-lead (Sn-Pb) alloy electrodes are fabricated by electrodeposition on a carbon paper with different alloy composition and used as cathode for electrocatalytic reduction of carbon dioxide into formate in an aqueous system. The prepared electrodes are measured by Faradaic efficiency and partial current density for formate production. Electrocatalytic reduction experiments are carried out at -1.8 V (vs. Ag/AgCl) using H-type cell under ambient temperature and pressure and the gas and liquid products are analyzed by gas chromatograph and liquid chromatograph, respectively. As results, the Sn-Pb electrodes show higher Faradaic efficiency and partial current density than the single metal electrode. The Sn-Pb alloy electrode which have Sn:Pb molar ratio=2:1, shows the highest Faradaic efficiency of 88.7%.

• Korean Chemical Engineering Research
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• v.52 no.1
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• pp.58-62
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• 2014

Electrochemical ammonia synthesis from water and nitrogen using a Pt/GDC/Pt cell was experimentally investigated. Electrochemical analysis and ammonia synthesis in the moisture-saturated nitrogen environment were performed under the operating temperature range $400{\sim}600^{\circ}C$ and the applied potential range OCV (Open Circuit Voltage)-1.2V. Even though the ammonia synthesis rate was augmented with the increase in the operating temperature (i.e. increase in the applied current) under the constant potential, the faradaic efficiency was decreased because of the limitation of dissociative chemisorption of nitrogen on the Pt electrode. The maximum synthesis rate of ammonia was $3.67{\times}10^{-11}mols^{-1}cm^{-2}$ with 0.1% faradaic efficiency at $600^{\circ}C$.

• Journal of Electrochemical Science and Technology
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• v.12 no.4
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• pp.406-414
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• 2021

Electrochemical devices are constructed for continuous syngas (CO + H₂) production with controlled selectivity between CO₂ and proton reduction reactions. The ratio of CO to H₂, or the faradaic efficiency toward CO generation, was mechanically manipulated by adjusting the space volume between the cathode and the polymer gas separator in the device. In particular, the area added between the cathode and the ion-conducting polymer using 0.5 M KHCO₃ catholyte regulated the solution acidity and proton reduction kinetics in the flow cell. The faradaic efficiency of CO production was controlled as a function of the distance between the polymer separator and cathode in addition to that manipulated by the electrode potential. Further, the electrochemical CO₂ reduction device using Au NPs presented a stable operation for more than 23 h at different H₂:CO production levels, demonstrating the functional stability of the flow cell utilizing the mechanical variable as an important operational factor.

• 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.

• Analytical Science and Technology
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• v.8 no.4
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• pp.683-689
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• 1995

Electrochemical reduction of carbon dioxide under high pressure on Fe electrodes and a gas diffusion electrode containing Pt catalyst (Pt-GDE) had been investigated. Formic acid was formed on Fe electrode with a faradaic efficiency of 60% at a current density of $120mA\;cm^{-2}$ under 30 atm of $CO_2$. Hydrocarbons such as $CH_4$, $C_2H_6$, $C_3H_6$, $1-C_4H_8$, and $n-C_5H_{12}$ are also formed. The distribution of hydrocarbons followed well the Schultz-Flory distribution. $CH_4$ was formed efficiently as the main reduction product on Pt-GDE.

• Journal of the Microelectronics and Packaging Society
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• v.30 no.4
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• pp.91-97
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• 2023

Electrochemical (EC) CO₂ reduction is a promising method to convert CO₂ into valuable hydrocarbon fuels and chemicals ecofriendly. Here, we report on a facile method to synthesize surface-controlled SnO₂/Cu(OH)₂ nanowires (NWs) and its EC reduction of CO₂ to HCOOH and CO. The SnO₂/Cu(OH)₂ NWs (-16 mA/cm²) showed superior electrochemical performance compared to Cu(OH)2 NWs (-6 mA/cm²) at -1.0 V (vs. RHE). SnO₂/Cu(OH)₂ NWs showed the maximum Faradaic efficiency for conversion to HCOOH (58.01 %) and CO (29.72 %). The optimized catalyst exhibits a high C1 Faradaic efficiency stable electrolysis for 2 h in a KHCO₃ electrolyte. This study facilitates the potential for the EC reduction of CO₂ to chemical fuels.

• Journal of the Korean Electrochemical Society
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• v.18 no.1
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• pp.24-30
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• 2015

To desalinate the aqueous solutions with high salt concentration using the capacitive deionization technology, two resin/membrane capacitive deionization(RMCDI) cells were fabricated by filling mixed ion exchange resins in two different flow channels (spacer and spiral type). The salt removal efficiency of the spacer- and spiral-RMCDI was 77.21 and 99.94%, respectively. Many ions were significantly removed in a spiral RMCDI cell because the feed solution could be more evenly contacted with the ion exchange resins filled on the spiral type flow channel. As the result of the changes of pH and accumulative charges, it was observed that Faradaic reaction was diminished for a spiral RMCDI cell filled by the mixture of cation and anion exchange resins. Therefore, the desalination of the aqueous solutions with high salt concentration by the capacitive deionization technology was proven. In addition, further studies on the optimization of the mixing ratio with ion exchange resins and the introduction of the regeneration process generally occurred in the continuous electrodeionization (CEDI) technology are required to improve the RMCDI technology.

• Applied Chemistry for Engineering
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• v.9 no.7
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• pp.998-1003
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• 1998

$BaTiO_3$ thin film was electrochemically deposited on Ti electrode in a 0.4 M $Ba(OH)_2$ solution of $85^{\circ}C$ using a current pulse waveform. Both $BaTiO_3$ crystallinity and faradaic efficiency for the film formation were enhanced with the increase of cathodic current density and pulse time. Based on the surface analysis and electrochemical studies, it was suggested that, during cathodic pulsed, the surface pH increase due to the reduction of $H_2O$ accelerates the structural changes of Ti oxides which were formed during anodic cycle. Prior to experiments, Ti oxides were intentionally grown in 0.1 M $H_2SO_4$ solution and the effect of initial oxide film thickness on the $BaTiO_3$ film formation was investigated. The migration of $Ti^{+4}$ ions through the oxide film was retarded with the increase of film thickness and it was observed that the crystallization of $BaTiO_3$ was only limited to the defect area of surface oxides.

• Journal of the Korean Electrochemical Society
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• v.17 no.1
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• pp.37-43
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• 2014

In this study, capacitive deionization (CDI) was introduced for desalination of mining water. Ion-exchange polymer coated carbon electrodes (IEE) were used in CDI to desalt mining water. The CDI performance using the IEE for desalination of mining water was carried out and then was compared with that using general carbon electrodes without ion-exchange polymer coating (GE). Moreover, to investigate the effect of the concentration of influent solutions on CDI performance, the CDI performance using the IEE for desalination of brackish water (NaCl 200 ppm) was also performed and analyzed. As a result, the higher salt removal efficiency, rate and the lower energy consumption in the CDI process using the IEE and mining water were obtained compared with those using the GE and mining water. It is mainly due to higher non-Faradaic current, low ohmic resistance of the influent, overlapping effect of electric double layers in micropore of the electrode. In addition, the CDI process using the IEE and brackish water shows much higher salt removal efficiency and lower salt removal rate than that using the IEE and mining water. This results from the lower concentration (i.e., higher ohmic resistance) and salt amount of the influent.

• Journal of the Korean Electrochemical Society
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• v.15 no.1
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• pp.41-47
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• 2012

An annular flow type of copper electrolysis reactor was setup in order to generate the copper ions to remove algae in water. The operating characteristics of the reactor and the effect of copper ion on algae have been considered. By controling the applied current, the copper ion concentration could be obtained as desired level and the faradaic efficiency was above 90%. When the flow rate was increased, the copper ion concentration was linearly decreased due to the dilution effect and the effect of concentration overpotential was insignificant. With the increase of pH in water, the copper ion concentration was linearly decreased and not affected by the conductivity of the water. The concentration of chlorophyll-a was sharply decreased with the increase of copper ion concentration. The algae was effectively removed as the copper ion concentration was above 0.2 ppm. There was no difference between the copper ions obtained by dissolving copper sulfate and those produced by copper electrolysis. The algae removal efficiency was above 90% after 5 days as the copper ion concentration was above 0.4 ppm.