• 대한화학회지
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• 제42권4호
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• pp.422-431
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• 1998

Salicyladehyde와 2-hydroxy-1-naphthaldehyde를 2-aminophenol과 2-amino-p-cresol에 반응시켜 세자리 Schiff base 리간드$(SIPH_2,\;SIPCH_2,\;HNIPH_2,\; HNIPCH_2)$들을 합성하였으며 이들 리간드를 Co(II) 이온과 반응시켜 세자리 Schiff base Co(II) 착물들을 합성하였다. 리간드와 착물들의 구조와 특성을 원소분석, $^1H$-NMR, IR, UV-vis 분광법과 열 무게 분석법으로 예측하였다. Co(II) 착물들은 Schiff base 리간드와 금속(II)의 몰비가 1:1로 결합하였으며, 3분자의 수화물이 배위된 6배위 착물 구조임을 알았다.지지 전해질로서 0.1M TBAP를 포함한 DMSO 용액에서 순환 전압전류법으로 세자리 Schiff base 리간드와 이들의 Co(II) 착물들의 전기 화학적인 산화·환원 과정을 알아보았다. 리간드들의 전기 화학적 환원은 확산 지배적이고 비가역적으로 진행되었으며 Co(II) 착물의 전기 화학적 환원과정은 2단계의 1전자 반응으로 확산 지배적이고 비가역적으로 진행되었다. Co(II) 착물들의 환원전위는 [Co(II)$(HNIPC)(H_2O)_3$]>[Co(II)$(HNIP)(H_2O)_3$]>[Co(II)$(SIPC)(H_2O)_3$]>[Co(II)$(SIP)(H_2O)_3] 순으로 약간 양전위 방향으로 이동하였으나 리간드의 영향은 크게 받지 않았다.

• 자원리싸이클링
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• 제10권6호
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• pp.9-14
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• 2001

폐리튬이온전지의 재활용 일환으로 양극활물질인 $LiCoO_2$로부터 Co와 Li을 회수하기 위하여 황산침출거동을 조사하였다. 황산 2M용액, $75^{\circ}C$ 조건에서 환원제를 첨가하지 않은 경우, $LiCoO_2$로부터 Li가 거의 100% 침출되는 반면에 Co는 같은 조건에서 40% 이하의 침출율을 보였다. Co의 침출율을 향상시키기 위하여 과산화수소를 환원제로 2~20 vol%범위에서 사용하였다 10 vol% 이상의 과산화수소를 첨가하였을 때, Co와 L거 침출율은 모두 95% 이상 이었다. 이는 환원제로서 과산화수소가 Co(III)를 Co(II)로 환원시켜 침출이 용이해졌기 때문으로 생각된다. 황산농도, 온도, 과산화수소 첨가량이 증가함에 따라 Co와 L리 침출율은 증가한 반면에 초기 광액농도가 증가할수록 Co와 L긴 침출율은 감소하였다. 이상의 조업변수 실험을 통하여 코발트계 리튬이온전지의 양극활물질인 $LiCoO_2$의 황산침출에서 황산농도 2 M, 침출온도 $75^{\circ}C$,초기광액농도 100 g/L, 과산화수소 첨가량 20 vol%에서 30분의반응시간이 침출 최적조건으로 생각된다.

• 한국세라믹학회지
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• 제55권1호
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• pp.50-54
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• 2018

This study investigated the long-term durability of catalyst(Pd or Fe)-infiltrated solid oxide cells for $CO_2$/steam co-electrolysis. Fuel-electrode supported solid oxide cells with dimensions of $5{\times}5cm^2$ were fabricated, and palladium or iron was subsequently introduced via wet infiltration (as a form of PdO or FeO solution). The metallic catalysts were employed in the fuel-electrode to promote $CO_2$ reduction via reverse water gas shift reactions. The metal-precursor particles were well-dispersed on the fuel-electrode substrate, which formed a bimetallic alloy with Ni embedded on the substrate during high-temperature reduction processes. These planar cells were tested using a mixture of $H_2O$ and $CO_2$ to measure the electrochemical and gas-production stabilities during 350 h of co-electrolysis operations. The results confirmed that compared to the Fe-infiltrated cell, the Pd-infiltrated cell had higher stabilities for both electrochemical reactions and gas-production given its resistance to carbon deposition.

• 한국분말재료학회지
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• 제5권4호
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• pp.334-339
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• 1998

In purpose of introducing the inverse magnetostrictive properties into the structural ceramics, $Al_2O_3$ based nanocomposites dispersed with nano-sized Ni-Co particles were studied. The composites were fabricated by the hydrogen reduction and hot-pressing of $Al_2O_3$ and NiO-CoO mixed powders. The mixtures were prepared by using Ni- and Co-nitrate $(Ni(NO_3)_2\;{\cdot}\;6H_2O\;and\;Co(NO_3)_2\;{\cdot}\6H_2O)$ as source materials for the Ni-Co particles. Microstructural observations revealed that nano-sized Ni-Co particles were dispersed homogeneously at $Al_2O_3$ grain boundaries. High strength above 1 GPa was obtained for the $Al_2O_3/10$ wt% Ni-Co nanocomposite fabricated by a controlled powder preparation process. The inverse magnetostrictive response to applied stress was obtained due to the presence of dispersed Ni-Co particles, which indicates a possibility to incorporate new functions into the structural ceramics without loosing the mechanical properties.

• 한국수소및신에너지학회논문집
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• 제14권3호
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• pp.268-275
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• 2003

The water-splitting process by the metal oxides using solar heat is one of the hydrogen production method. The hydrogen production process using the metal oxides (NiFe2O4/NiAl2O4,CoFe2O4/CoAl2O4, CoMnNiFerrite, CoMnSnFerrite, CoMnZnFerrite, CoSnZnFerrite) was carried out by two steps. The first step was carried out by the CH4-reduction to increase activation of metal oxides at operation temperature. And then, it was carried out the water-splitting reaction using the water at operation temperature for the second step. Hydrogen was produced in this step. The production rates of H2 were 110, 160, 72, 29, 17, $21m{\ell}/hr{\cdot}g-_{Metal\;Oxide}$ for NiFe2O4/NiAl2O4, CoFe2O4/CoAl2O4, CoMnNiFerrite, CoMnSnFerrite, CoMnZnFerrite, CoSnZnFerrite respectively in the second step. CoFe2O4/CoAl2O4 had higher H2 production rate than the other metal oxides.

• 마이크로전자및패키징학회지
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• 제30권4호
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• pp.91-97
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• 2023

전기화학적 이산화탄소 (CO₂) 환원은 CO₂를 고부가가치의 탄소화합물로 전환하는 매우 유망한 방법이다. 본 논문에서는 양극 산화법과 원자층 증착법을 이용하여 전기화학적 CO₂ 환원용 SnO₂/Cu(OH)₂ 나노와이어 (NWs) 전극을 합성하는 손쉬운 방법과 그 특성에 대해 보고한다. 제작된 SnO₂/Cu(OH)₂ NWs (-16 mA/cm²)는 -1.0 V (vs. RHE)에서 Cu(OH)₂ NWs (-6 mA/cm²) 대비 더 우수한 전기화학적 성능을 보였다. CO₂ 환원 성능을 확인해 보았을 때도 일산화탄소(CO), 포름산염 (HCOOH) 생성물에 대해 각각 29.72 %, 58.01 %의 높은 페러데이 효율 (FE)을 보였다. 본 연구는 CO₂ 배출로 인한 기후 변화에 대응하는 경제적이며 지속 가능한 방법을 제공할 뿐만 아니라, 전기화학적 CO₂ 환원용 전극 개발에 크게 기여할 것으로 예상된다.

• 한국수소및신에너지학회논문집
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• 제17권3호
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• pp.309-316
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• 2006

Co-ferrite was synthesized by HEBM (High Energy Ball Milling) with a stoichiometric (Co/Fe=0.5/2.5) mixture of CoO and $Fe_2O_3$ powders. The effect of milling time on the phase transformation of the mixture was investigated by XRD. Mono-phase solid solution of Co-ferrite, which was milled for 4 h and then calcined at $900^{\circ}C$ in the Ar atmosphere, was confirmed by XRD analysis. The composition and thermal reduction behavior of Co-ferrite were analyzed by TGA and XRF. As a result, oxygen deficient Co-ferrite was synthesized by HEBM and the weight decrease of the Co-ferrite, which was oxidized at $600^{\circ}C$ for 10h by $H_2O$ vapor, was 2.41 wt% during thermal reduction at $1300^{\circ}C$.

• 한국수소및신에너지학회논문집
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• 제14권1호
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• pp.24-34
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• 2003

For gaseous fuel combustion with inherent $CO_2$ capture and low NOx emission, chemical-looping combustion may yield great advantages for the savings of energy to $CO_2$ separation and suppressing the effect on environment, In chemical-looping combustor, fuel is oxidized by metal oxide medium in a reduction reactor. Reduced particles are transported to oxidation reactor and oxidized by air and recycled to reduction reactor. The fuel and the air are never mixed, and the gases from reduction reactor, $CO_2$ and $H_2O$, leave the system as separate stream. The $H_2O$ can be easily separated by condensation and pure $CO_2$ is obtained without any loss of energy for separation. In this study, five oxygen carrier particles such as NiO/bentonite, NiO/YSZ, $(NiO+Fe_2O_3)VYSZ$, $NiO/NiAl_2O_4$, and $Co_{\chi}O_y/CoAl_2O_4$ were examined &om the viewpoints of reaction kinetics, oxygen transfer capacity, and carbon deposition characteristics. Among five oxygen particles, NiO/YSZ particle is superior in reaction rate, oxygen carrier capacity, and carbon deposition to other particles. However, at high temperature ($>900^{\circ}C$), NiO/bentonite particle also shows enough reactivity and oxygen carrier capacity to be applied in a practical system.

• 마이크로전자및패키징학회지
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• 제27권4호
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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.

• 한국재료학회지
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• 제22권5호
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• pp.253-258
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• 2012

Activated magnetite ($Fe_3O_{4-{\delta}}$) was applied to reducing $CO_2$ gas emissions to avoid greenhouse effects. Wet and dry methods were developed as a $CO_2$ removal process. One of the typical dry methods is $CO_2$ decomposition using activated magnetite ($Fe_3O_{4-{\delta}}$). Generally, $Fe_3O_{4-{\delta}}$ is manufactured by reduction of $Fe_3O_4$ by $H_2$ gas. This process has an explosion risk. Therefore, a non-explosive process to make $Fe_3O_{4-{\delta}}$ was studied using $FeC_2O_4{\cdot}2H_2O$ and $N_2$. $FeSO_4{\cdot}7H_2O$ and $(NH_4)_2C_2O_4{\cdot}H_2O$ were used as starting materials. So, ${\alpha}-FeC_2O_4{\cdot}2H_2O$ was synthesized by precipitation method. During the calcination process, $FeC_2O_4{\cdot}2H_2O$ was decomposed to $Fe_3O_4$, CO, and $CO_2$. The specific surface area of the activated magnetite varied with the calcination temperature from 15.43 $m^2/g$ to 9.32 $m^2/g$. The densities of $FeC_2O_4{\cdot}2H_2O$ and $Fe_3O_4$ were 2.28 g/$cm^3$ and 5.2 g/$cm^3$, respectively. Also, the $Fe_3O_4$ was reduced to $Fe_3O_{4-{\delta}}$ by CO. From the TGA results in air of the specimen that was calcined at $450^{\circ}C$ for three hours in $N_2$ atmosphere, the ${\delta}$-value of $Fe_3O_{4-{\delta}}$ was estimated. The ${\delta}$-value of $Fe_3O_{4-{\delta}}$ was 0.3170 when the sample was heat treated at $400^{\circ}C$ for 3 hours and 0.6583 when the sample was heat treated at $450^{\circ}C$ for 3 hours. $Fe_3O_{4-{\delta}}$ was oxidized to $Fe_3O_4$ when $Fe_3O_{4-{\delta}}$ was reacted with $CO_2$ because $CO_2$ is decomposed to C and $O_2$.